Vineet Gupta [Wed, 21 Oct 2015 22:03:12 +0000 (09:03 +1100)]
mm: optimize PageHighMem() check
This came up when implementing HIHGMEM/PAE40 for ARC. The kmap() /
kmap_atomic() generated code seemed needlessly bloated due to the way
PageHighMem() macro is implemented. It derives the exact zone for page
and then does pointer subtraction with first zone to infer the zone_type.
The pointer arithmatic in turn generates the code bloat.
Oleg Nesterov [Wed, 21 Oct 2015 22:03:11 +0000 (09:03 +1100)]
mm/oom_kill: fix the wrong task->mm == mm checks in oom_kill_process()
Both "child->mm == mm" and "p->mm != mm" checks in oom_kill_process() are
wrong. task->mm can be NULL if the task is the exited group leader. This
means in particular that "kill sharing same memory" loop can miss a
process with a zombie leader which uses the same ->mm.
Note: the process_has_mm(child, p->mm) check is still not 100% correct,
p->mm can be NULL too. This is minor, but probably deserves a fix or a
comment anyway.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Kyle Walker <kwalker@redhat.com> Cc: Stanislav Kozina <skozina@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Wed, 21 Oct 2015 22:03:11 +0000 (09:03 +1100)]
mm/oom_kill: cleanup the "kill sharing same memory" loop
Purely cosmetic, but the complex "if" condition looks annoying to me.
Especially because it is not consistent with OOM_SCORE_ADJ_MIN check
which adds another if/continue.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Kyle Walker <kwalker@redhat.com> Cc: Stanislav Kozina <skozina@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Wed, 21 Oct 2015 22:03:11 +0000 (09:03 +1100)]
mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process()
The fatal_signal_pending() was added to suppress unnecessary "sharing same
memory" message, but it can't 100% help anyway because it can be
false-negative; SIGKILL can be already dequeued.
And worse, it can be false-positive due to exec or coredump. exec is
mostly fine, but coredump is not. It is possible that the group leader
has the pending SIGKILL because its sub-thread originated the coredump, in
this case we must not skip this process.
We could probably add the additional ->group_exit_task check but this
patch just removes the wrong check along with pr_info().
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Kyle Walker <kwalker@redhat.com> Cc: Stanislav Kozina <skozina@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Wed, 21 Oct 2015 22:03:10 +0000 (09:03 +1100)]
mm: fix the racy mm->locked_vm change in
"mm->locked_vm += grow" and vm_stat_account() in acct_stack_growth() are
not safe; multiple threads using the same ->mm can do this at the same
time trying to expans different vma's under down_read(mmap_sem). This
means that one of the "locked_vm += grow" changes can be lost and we can
miss munlock_vma_pages_all() later.
Move this code into the caller(s) under mm->page_table_lock. All other
updates to ->locked_vm hold mmap_sem for writing.
Make zone_pagecache_reclaimable() return ulong rather than long. Negative
values are meainingless here and all zone_pagecache_reclaimable() callers
turn its retrun value into ulong anyway.
Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Alexandru Moise <00moses.alexander00@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alexandru Moise [Wed, 21 Oct 2015 22:03:10 +0000 (09:03 +1100)]
mm/vmscan.c: fix types of some locals
In zone_reclaimable_pages(), `nr' is returned by a function which is
declared as returning "unsigned long", so declare it such. Negative
values are meaningless here.
In zone_pagecache_reclaimable() we should also declare `delta' and
`nr_pagecache_reclaimable' as being unsigned longs because they're used to
store the values returned by zone_page_state() and
zone_unmapped_file_pages() which also happen to return unsigned integers.
Signed-off-by: Alexandru Moise <00moses.alexander00@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This patch address minor comment nitpicks from Vlastimil. It is a fix for the
mmotm patch
mm-page_alloc-hide-some-GFP-internals-and-document-the-bit-and-flag-combinations.patch
Mel Gorman [Wed, 21 Oct 2015 22:03:09 +0000 (09:03 +1100)]
mm: page_alloc: hide some GFP internals and document the bits and flag combinations
Andrew stated the following
We have quite a history of remote parts of the kernel using
weird/wrong/inexplicable combinations of __GFP_ flags. I tend
to think that this is because we didn't adequately explain the
interface.
And I don't think that gfp.h really improved much in this area as
a result of this patchset. Could you go through it some time and
decide if we've adequately documented all this stuff?
This patches first moves some GFP flag combinations that are part of the MM
internals to mm/internal.h. The rest of the patch documents the __GFP_FOO
bits under various headings and then documents the flag combinations. It
will not help callers that are brain damaged but the clarity might motivate
some fixes and avoid future mistakes.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:09 +0000 (09:03 +1100)]
mm, page_alloc: only enforce watermarks for order-0 allocations -fix
This patch is updating comments for clarity and converts a bool to an int.
The code as-is is ok as the compiler is meant to cast it correctly but it
looks odd to people who know the value would be truncated and lost for
other types.
This is a fix to the mmotm patch
mm-page_alloc-only-enforce-watermarks-for-order-0-allocations.patch
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:09 +0000 (09:03 +1100)]
mm, page_alloc: only enforce watermarks for order-0 allocations
The primary purpose of watermarks is to ensure that reclaim can always
make forward progress in PF_MEMALLOC context (kswapd and direct reclaim).
These assume that order-0 allocations are all that is necessary for
forward progress.
High-order watermarks serve a different purpose. Kswapd had no high-order
awareness before they were introduced
(https://lkml.kernel.org/r/413AA7B2.4000907@yahoo.com.au). This was
particularly important when there were high-order atomic requests. The
watermarks both gave kswapd awareness and made a reserve for those atomic
requests.
There are two important side-effects of this. The most important is that
a non-atomic high-order request can fail even though free pages are
available and the order-0 watermarks are ok. The second is that
high-order watermark checks are expensive as the free list counts up to
the requested order must be examined.
With the introduction of MIGRATE_HIGHATOMIC it is no longer necessary to
have high-order watermarks. Kswapd and compaction still need high-order
awareness which is handled by checking that at least one suitable
high-order page is free.
With the patch applied, there was little difference in the allocation
failure rates as the atomic reserves are small relative to the number of
allocation attempts. The expected impact is that there will never be an
allocation failure report that shows suitable pages on the free lists.
The one potential side-effect of this is that in a vanilla kernel, the
watermark checks may have kept a free page for an atomic allocation. Now,
we are 100% relying on the HighAtomic reserves and an early allocation to
have allocated them. If the first high-order atomic allocation is after
the system is already heavily fragmented then it'll fail.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
yalin wang [Wed, 21 Oct 2015 22:03:09 +0000 (09:03 +1100)]
mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand -fix
There is a redundant check and a memory leak introduced by a patch in
mmotm. This patch removes an unlikely(order) check as we are sure order
is not zero at the time. It also checks if a page is already allocated to
avoid a memory leak.
This is a fix to the mmotm patch
mm-page_alloc-reserve-pageblocks-for-high-order-atomic-allocations-on-demand.patch
Signed-off-by: yalin wang <yalin.wang2010@gmail.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:08 +0000 (09:03 +1100)]
mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand -fix
nr_reserved_highatomic is checked outside the zone lock so there is a race
whereby the reserve is larger than the limit allows. This patch rechecks
the count under the zone lock.
During unreserving, there is a possibility we could underflow if there
ever was a race between per-cpu drains, reserve and unreserving. This
patch adds a comment about the potential race and protects against it.
These are two fixes to the mmotm patch
mm-page_alloc-reserve-pageblocks-for-high-order-atomic-allocations-on-demand.patch
. They are not separate patches and they should all be folded together.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:08 +0000 (09:03 +1100)]
mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand
High-order watermark checking exists for two reasons -- kswapd high-order
awareness and protection for high-order atomic requests. Historically the
kernel depended on MIGRATE_RESERVE to preserve min_free_kbytes as
high-order free pages for as long as possible. This patch introduces
MIGRATE_HIGHATOMIC that reserves pageblocks for high-order atomic
allocations on demand and avoids using those blocks for order-0
allocations. This is more flexible and reliable than MIGRATE_RESERVE was.
A MIGRATE_HIGHORDER pageblock is created when an atomic high-order
allocation request steals a pageblock but limits the total number to 1% of
the zone. Callers that speculatively abuse atomic allocations for
long-lived high-order allocations to access the reserve will quickly fail.
Note that SLUB is currently not such an abuser as it reclaims at least
once. It is possible that the pageblock stolen has few suitable
high-order pages and will need to steal again in the near future but there
would need to be strong justification to search all pageblocks for an
ideal candidate.
The pageblocks are unreserved if an allocation fails after a direct
reclaim attempt.
The watermark checks account for the reserved pageblocks when the
allocation request is not a high-order atomic allocation.
The reserved pageblocks can not be used for order-0 allocations. This may
allow temporary wastage until a failed reclaim reassigns the pageblock.
This is deliberate as the intent of the reservation is to satisfy a
limited number of atomic high-order short-lived requests if the system
requires them.
The stutter benchmark was used to evaluate this but while it was running
there was a systemtap script that randomly allocated between 1 high-order
page and 12.5% of memory's worth of order-3 pages using GFP_ATOMIC. This
is much larger than the potential reserve and it does not attempt to be
realistic. It is intended to stress random high-order allocations from an
unknown source, show that there is a reduction in failures without
introducing an anomaly where atomic allocations are more reliable than
regular allocations. The amount of memory reserved varied throughout the
workload as reserves were created and reclaimed under memory pressure.
The allocation failures once the workload warmed up were as follows;
4.2-rc5-vanilla 70%
4.2-rc5-atomic-reserve 56%
The failure rate was also measured while building multiple kernels. The
failure rate was 14% but is 6% with this patch applied.
Overall, this is a small reduction but the reserves are small relative to
the number of allocation requests. In early versions of the patch, the
failure rate reduced by a much larger amount but that required much larger
reserves and perversely made atomic allocations seem more reliable than
regular allocations.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:08 +0000 (09:03 +1100)]
mm, page_alloc: remove MIGRATE_RESERVE
MIGRATE_RESERVE preserves an old property of the buddy allocator that
existed prior to fragmentation avoidance -- min_free_kbytes worth of pages
tended to remain contiguous until the only alternative was to fail the
allocation. At the time it was discovered that high-order atomic
allocations relied on this property so MIGRATE_RESERVE was introduced. A
later patch will introduce an alternative MIGRATE_HIGHATOMIC so this patch
deletes MIGRATE_RESERVE and supporting code so it'll be easier to review.
Note that this patch in isolation may look like a false regression if
someone was bisecting high-order atomic allocation failures.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:08 +0000 (09:03 +1100)]
mm, page_alloc: delete the zonelist_cache
The zonelist cache (zlc) was introduced to skip over zones that were
recently known to be full. This avoided expensive operations such as the
cpuset checks, watermark calculations and zone_reclaim. The situation
today is different and the complexity of zlc is harder to justify.
1) The cpuset checks are no-ops unless a cpuset is active and in general
are a lot cheaper.
2) zone_reclaim is now disabled by default and I suspect that was a large
source of the cost that zlc wanted to avoid. When it is enabled, it's
known to be a major source of stalling when nodes fill up and it's
unwise to hit every other user with the overhead.
3) Watermark checks are expensive to calculate for high-order
allocation requests. Later patches in this series will reduce the cost
of the watermark checking.
4) The most important issue is that in the current implementation it
is possible for a failed THP allocation to mark a zone full for order-0
allocations and cause a fallback to remote nodes.
The last issue could be addressed with additional complexity but as the
benefit of zlc is questionable, it is better to remove it. If stalls due
to zone_reclaim are ever reported then an alternative would be to
introduce deferring logic based on a timeout inside zone_reclaim itself
and leave the page allocator fast paths alone.
The impact on page-allocator microbenchmarks is negligible as they don't
hit the paths where the zlc comes into play. Most page-reclaim related
workloads showed no noticeable difference as a result of the removal.
The impact was noticeable in a workload called "stutter". One part uses a
lot of anonymous memory, a second measures mmap latency and a third copies
a large file. In an ideal world the latency application would not notice
the mmap latency. On a 2-node machine the results of this patch are
Note that the maximum stall latency went from 24 seconds to 12 which is
still bad but an improvement. The milage varies considerably 2-node
machine on an earlier test went from 494 seconds to 47 seconds and a
4-node machine that tested an earlier version of this patch went from a
worst case stall time of 6 seconds to 67ms. The nature of the benchmark
is inherently unpredictable as it is hammering the system and the milage
will vary between machines.
There is a secondary impact with potentially more direct reclaim because
zones are now being considered instead of being skipped by zlc. In this
particular test run it did not occur so will not be described. However,
in at least one test the following was observed
1. Direct reclaim rates were higher. This was likely due to direct reclaim
being entered instead of the zlc disabling a zone and busy looping.
Busy looping may have the effect of allowing kswapd to make more
progress and in some cases may be better overall. If this is found then
the correct action is to put direct reclaimers to sleep on a waitqueue
and allow kswapd make forward progress. Busy looping on the zlc is even
worse than when the allocator used to blindly call congestion_wait().
2. There was higher swap activity as direct reclaim was active.
3. Direct reclaim efficiency was lower. This is related to 1 as more
scanning activity also encountered more pages that could not be
immediately reclaimed
In that case, the direct page scan and reclaim rates are noticeable but
it is not considered a problem for a few reasons
1. The test is primarily concerned with latency. The mmap attempts are also
faulted which means there are THP allocation requests. The ZLC could
cause zones to be disabled causing the process to busy loop instead
of reclaiming. This looks like elevated direct reclaim activity but
it's the correct action to take based on what processes requested.
2. The test hammers reclaim and compaction heavily. The number of successful
THP faults is highly variable but affects the reclaim stats. It's not a
realistic or reasonable measure of page reclaim activity.
3. No other page-reclaim intensive workload that was tested showed a problem.
4. If a workload is identified that benefitted from the busy looping then it
should be fixed by having direct reclaimers sleep on a wait queue until
woken by kswapd instead of busy looping. We had this class of problem before
when congestion_waits() with a fixed timeout was a brain damaged decision
but happened to benefit some workloads.
If a workload is identified that relied on the zlc to busy loop then it
should be fixed correctly and have a direct reclaimer sleep on a waitqueue
until woken by kswapd.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
WARNING: line over 80 characters
#110: FILE: drivers/block/drbd/drbd_bitmap.c:1010:
+ page = mempool_alloc(drbd_md_io_page_pool, __GFP_HIGHMEM|__GFP_RECLAIM);
WARNING: line over 80 characters
#139: FILE: drivers/block/nvme-core.c:1039:
+ ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen, __GFP_RECLAIM);
WARNING: line over 80 characters
#466: FILE: include/linux/gfp.h:110:
+#define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM))
ERROR: code indent should use tabs where possible
#547: FILE: kernel/power/swap.c:978:
+^I^I __get_free_page(__GFP_RECLAIM | __GFP_HIGH);$
ERROR: code indent should use tabs where possible
#557: FILE: kernel/power/swap.c:1245:
+^I^I __GFP_RECLAIM | __GFP_HIGH :$
ERROR: code indent should use tabs where possible
#558: FILE: kernel/power/swap.c:1246:
+^I^I __GFP_RECLAIM | __GFP_NOWARN |$
WARNING: line over 80 characters
#570: FILE: lib/percpu_ida.c:138:
+ * used for internal memory allocations); thus if passed __GFP_RECLAIM we may sleep
ERROR: code indent should use tabs where possible
#596: FILE: mm/failslab.c:19:
+ if (failslab.ignore_gfp_reclaim && (gfpflags & __GFP_RECLAIM))$
WARNING: please, no spaces at the start of a line
#596: FILE: mm/failslab.c:19:
+ if (failslab.ignore_gfp_reclaim && (gfpflags & __GFP_RECLAIM))$
WARNING: line over 80 characters
#617: FILE: mm/filemap.c:2717:
+ * this page (__GFP_IO), and whether the call may block (__GFP_RECLAIM & __GFP_FS).
total: 4 errors, 6 warnings, 463 lines checked
NOTE: Whitespace errors detected.
You may wish to use scripts/cleanpatch or scripts/cleanfile
./patches/mm-page_alloc-rename-__gfp_wait-to-__gfp_reclaim.patch has style problems, please review.
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
Please run checkpatch prior to sending patches
Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:07 +0000 (09:03 +1100)]
mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM
__GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep. Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep. The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake. As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags. This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:07 +0000 (09:03 +1100)]
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts. They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve". __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".
Over time, callers had a requirement to not block when fallback options
were available. Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.
This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative. High priority users continue to use
__GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim. __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.
This patch then converts a number of sites
o __GFP_ATOMIC is used by callers that are high priority and have memory
pools for those requests. GFP_ATOMIC uses this flag.
o Callers that have a limited mempool to guarantee forward progress clear
__GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
into this category where kswapd will still be woken but atomic reserves
are not used as there is a one-entry mempool to guarantee progress.
o Callers that are checking if they are non-blocking should use the
helper gfpflags_allow_blocking() where possible. This is because
checking for __GFP_WAIT as was done historically now can trigger false
positives. Some exceptions like dm-crypt.c exist where the code intent
is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
flag manipulations.
o Callers that built their own GFP flags instead of starting with GFP_KERNEL
and friends now also need to specify __GFP_KSWAPD_RECLAIM.
The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.
The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL. They may
now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:07 +0000 (09:03 +1100)]
mm, page_alloc: use masks and shifts when converting GFP flags to migrate types
This patch redefines which GFP bits are used for specifying mobility and
the order of the migrate types. Once redefined it's possible to convert
GFP flags to a migrate type with a simple mask and shift. The only
downside is that readers of OOM kill messages and allocation failures may
have been used to the existing values but scripts/gfp-translate will help.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:06 +0000 (09:03 +1100)]
mm, page_alloc: remove unnecessary taking of a seqlock when cpusets are disabled
There is a seqcounter that protects against spurious allocation failures
when a task is changing the allowed nodes in a cpuset. There is no need
to check the seqcounter until a cpuset exists.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:06 +0000 (09:03 +1100)]
mm, page_alloc: remove unnecessary recalculations for dirty zone balancing
File-backed pages that will be immediately written are balanced between
zones. This heuristic tries to avoid having a single zone filled with
recently dirtied pages but the checks are unnecessarily expensive. Move
consider_zone_balanced into the alloc_context instead of checking bitmaps
multiple times. The patch also gives the parameter a more meaningful
name.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Wed, 21 Oct 2015 22:03:06 +0000 (09:03 +1100)]
mm, page_alloc: remove unnecessary parameter from zone_watermark_ok_safe
Overall, the intent of this series is to remove the zonelist cache which
was introduced to avoid high overhead in the page allocator. Once this is
done, it is necessary to reduce the cost of watermark checks.
The series starts with minor micro-optimisations.
Next it notes that GFP flags that affect watermark checks are abused.
__GFP_WAIT historically identified callers that could not sleep and could
access reserves. This was later abused to identify callers that simply
prefer to avoid sleeping and have other options. A patch distinguishes
between atomic callers, high-priority callers and those that simply wish
to avoid sleep.
The zonelist cache has been around for a long time but it is of dubious
merit with a lot of complexity and some issues that are explained. The
most important issue is that a failed THP allocation can cause a zone to
be treated as "full". This potentially causes unnecessary stalls, reclaim
activity or remote fallbacks. The issues could be fixed but it's not
worth it. The series places a small number of other micro-optimisations
on top before examining GFP flags watermarks.
High-order watermarks enforcement can cause high-order allocations to fail
even though pages are free. The watermark checks both protect high-order
atomic allocations and make kswapd aware of high-order pages but there is
a much better way that can be handled using migrate types. This series
uses page grouping by mobility to reserve pageblocks for high-order
allocations with the size of the reservation depending on demand. kswapd
awareness is maintained by examining the free lists. By patch 12 in this
series, there are no high-order watermark checks while preserving the
properties that motivated the introduction of the watermark checks.
This patch (of 10):
No user of zone_watermark_ok_safe() specifies alloc_flags. This patch
removes the unnecessary parameter.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Christoph Lameter <cl@linux.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Rientjes [Wed, 21 Oct 2015 22:03:06 +0000 (09:03 +1100)]
mm, oom: remove task_lock protecting comm printing
The oom killer takes task_lock() in a couple of places solely to protect
printing the task's comm.
A process's comm, including current's comm, may change due to
/proc/pid/comm or PR_SET_NAME.
The comm will always be NULL-terminated, so the worst race scenario would
only be during update. We can tolerate a comm being printed that is in
the middle of an update to avoid taking the lock.
Other locations in the kernel have already dropped task_lock() when
printing comm, so this is consistent.
Signed-off-by: David Rientjes <rientjes@google.com> Suggested-by: Oleg Nesterov <oleg@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vlastimil Babka [Wed, 21 Oct 2015 22:03:06 +0000 (09:03 +1100)]
mm, compaction: distinguish contended status in tracepoints
Compaction returns prematurely with COMPACT_PARTIAL when contended or has
fatal signal pending. This is ok for the callers, but might be misleading
in the traces, as the usual reason to return COMPACT_PARTIAL is that we
think the allocation should succeed. After this patch we distinguish the
premature ending condition in the mm_compaction_finished and
mm_compaction_end tracepoints.
The contended status covers the following reasons:
- lock contention or need_resched() detected in async compaction
- fatal signal pending
- too many pages isolated in the zone (only for async compaction)
Further distinguishing the exact reason seems unnecessary for now.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vlastimil Babka [Wed, 21 Oct 2015 22:03:05 +0000 (09:03 +1100)]
mm, compaction: export tracepoints zone names to userspace-fix
Through undertaker-checkpatch it was reported that HighMem would be
missing in the tracepoint output due to checking CONFIG_ZONE_HIGHMEM_
instead of CONFIG_HIGHMEM. Fix it.
Vlastimil Babka [Wed, 21 Oct 2015 22:03:05 +0000 (09:03 +1100)]
mm, compaction: export tracepoints zone names to userspace
Some compaction tracepoints use zone->name to print which zone is being
compacted. This works for in-kernel printing, but not userspace trace
printing of raw captured trace such as via trace-cmd report.
This patch uses zone_idx() instead of zone->name as the raw value, and
when printing, converts the zone_type to string using the appropriate EM()
macros and some ugly tricks to overcome the problem that half the values
depend on CONFIG_ options and one does not simply use #ifdef inside of
#define.
Vlastimil Babka [Wed, 21 Oct 2015 22:03:05 +0000 (09:03 +1100)]
mm, compaction: export tracepoints status strings to userspace
Some compaction tracepoints convert the integer return values to strings
using the compaction_status_string array. This works for in-kernel
printing, but not userspace trace printing of raw captured trace such as
via trace-cmd report.
This patch converts the private array to appropriate tracepoint macros
that result in proper userspace support.
Tetsuo Handa [Wed, 21 Oct 2015 22:03:05 +0000 (09:03 +1100)]
mm/oom_kill.c: suppress unnecessary "sharing same memory" message
oom_kill_process() sends SIGKILL to other thread groups sharing victim's
mm. But printing
"Kill process %d (%s) sharing same memory\n"
lines makes no sense if they already have pending SIGKILL. This patch
reduces the "Kill process" lines by printing that line with info level
only if SIGKILL is not pending.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
oom_kill_process() does atomic_inc(&mm->mm_users) to ensure that this ->mm
can't go away and this is wrong, change it to rely on ->mm_count and
mmdrop().
Firstly, we do not want to delay exit_mmap/etc if the victim exits before
we do mmput(), but this is minor.
More importantly, we simply can not do mmput() in oom_kill_process(), this
can deadlock if (for example) the caller holds i_mmap_rwsem and mmput()
actually leads to exit_mmap(); the victim can have this file mmaped and in
this case unmap_vmas/free_pgtables paths will take the same lock for
writing. And at least huge_pmd_share() does pmd_alloc() under
i_mmap_rwsem because VM_HUGETLB memory is not reclaimable.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: David Rientjes <rientjes@google.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tetsuo Handa [Wed, 21 Oct 2015 22:03:05 +0000 (09:03 +1100)]
mm/oom_kill.c: fix potentially killing unrelated process
At the for_each_process() loop in oom_kill_process(), we are comparing
address of OOM victim's mm without holding a reference to that mm. If
there are a lot of processes to compare or a lot of "Kill process %d (%s)
sharing same memory" messages to print, for_each_process() loop could take
very long time.
It is possible that meanwhile the OOM victim exits and releases its mm,
and then mm is allocated with the same address and assigned to some
unrelated process. When we hit such race, the unrelated process will be
killed by error. To make sure that the OOM victim's mm does not go away
until for_each_process() loop finishes, get a reference on the OOM
victim's mm before calling task_unlock(victim).
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tetsuo Handa [Wed, 21 Oct 2015 22:03:04 +0000 (09:03 +1100)]
mm/oom_kill.c: reverse the order of setting TIF_MEMDIE and sending SIGKILL
It was confirmed that a local unprivileged user can consume all memory
reserves and hang up that system using time lag between the OOM killer
sets TIF_MEMDIE on an OOM victim and sends SIGKILL to that victim, for
printk() inside for_each_process() loop at oom_kill_process() can consume
many seconds when there are many thread groups sharing the same memory.
The oom-depleter's thread group leader which got TIF_MEMDIE started
memset() in user space after the OOM killer set TIF_MEMDIE, and it was
free to abuse ALLOC_NO_WATERMARKS by TIF_MEMDIE for memset() in user space
until SIGKILL is delivered. If SIGKILL is delivered before TIF_MEMDIE is
set, the oom-depleter can terminate without touching memory reserves.
Although the possibility of hitting this time lag is very small for 3.19
and earlier kernels because TIF_MEMDIE is set immediately before sending
SIGKILL, preemption or long interrupts (an extreme example is SysRq-t) can
step between and allow memory allocations which are not needed for
terminating the OOM victim.
Fixes: 83363b917a29 ("oom: make sure that TIF_MEMDIE is set under task_lock") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> [4.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
A higher value can cause excessive swap IO and waste memory. A lower
value can prevent THPs from being collapsed, resulting fewer pages being
collapsed into THPs, and lower memory access performance.
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jerome Marchand [Wed, 21 Oct 2015 22:03:03 +0000 (09:03 +1100)]
mm/memcontrol.c: fix order calculation in try_charge()
Since 6539cc05386 ("mm: memcontrol: fold mem_cgroup_do_charge()"), the
order to pass to mem_cgroup_oom() is calculated by passing the number of
pages to get_order() instead of the expected size in bytes. AFAICT, it
only affects the value displayed in the oom warning message. This patch
fix this.
Michal said:
: We haven't noticed that just because the OOM is enabled only for page
: faults of order-0 (single page) and get_order work just fine. Thanks for
: noticing this. If we ever start triggering OOM on different orders this
: would be broken.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Naoya Horiguchi [Wed, 21 Oct 2015 22:03:03 +0000 (09:03 +1100)]
mm: hwpoison: ratelimit messages from unpoison_memory()
Currently kernel prints out results of every single unpoison event, which
i= s not necessary because unpoison is purely a testing feature and
testers can = get little or no information from lots of lines of unpoison
log storm. So this patch ratelimits printk in unpoison_memory().
This patch introduces a file local ratelimit_state, which adds 64 bytes to
memory-failure.o. If we apply pr_info_ratelimited() for 8 callsite below,
2= 56 bytes is added, so it's a win.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Junichi Nomura [Wed, 21 Oct 2015 22:03:03 +0000 (09:03 +1100)]
mm/filemap.c: make global sync not clear error status of individual inodes
filemap_fdatawait() is a function to wait for on-going writeback to
complete but also consume and clear error status of the mapping set during
writeback.
The latter functionality is critical for applications to detect writeback
error with system calls like fsync(2)/fdatasync(2).
However filemap_fdatawait() is also used by sync(2) or FIFREEZE ioctl,
which don't check error status of individual mappings.
As a result, fsync() may not be able to detect writeback error if events
happen in the following order:
Application System admin
----------------------------------------------------------
write data on page cache
Run sync command
writeback completes with error
filemap_fdatawait() clears error
fsync returns success
(but the data is not on disk)
This patch adds filemap_fdatawait_keep_errors() for call sites where
writeback error is not handled so that they don't clear error status.
Yaowei Bai [Wed, 21 Oct 2015 22:03:03 +0000 (09:03 +1100)]
mm/oom_kill.c: introduce is_sysrq_oom helper
Introduce is_sysrq_oom helper function indicating oom kill triggered
by sysrq to improve readability.
No functional changes.
Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Naoya Horiguchi [Wed, 21 Oct 2015 22:03:02 +0000 (09:03 +1100)]
mm: hugetlb: proc: add HugetlbPages field to /proc/PID/status
Currently there's no easy way to get per-process usage of hugetlb pages,
which is inconvenient because userspace applications which use hugetlb
typically want to control their processes on the basis of how much memory
(including hugetlb) they use. So this patch simply provides easy access
to the info via /proc/PID/status.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Joern Engel <joern@logfs.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Naoya Horiguchi [Wed, 21 Oct 2015 22:03:02 +0000 (09:03 +1100)]
mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps
Currently /proc/PID/smaps provides no usage info for vma(VM_HUGETLB), which
is inconvenient when we want to know per-task or per-vma base hugetlb usage.
To solve this, this patch adds new fields for hugetlb usage like below:
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Joern Engel <joern@logfs.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Roman Gushchin [Wed, 21 Oct 2015 22:03:02 +0000 (09:03 +1100)]
mm: use only per-device readahead limit
Maximal readahead size is limited now by two values:
1) by global 2Mb constant (MAX_READAHEAD in max_sane_readahead())
2) by configurable per-device value* (bdi->ra_pages)
There are devices, which require custom readahead limit.
For instance, for RAIDs it's calculated as number of devices
multiplied by chunk size times 2.
Readahead size can never be larger than bdi->ra_pages * 2 value
(POSIX_FADV_SEQUNTIAL doubles readahead size).
If so, why do we need two limits?
I suggest to completely remove this max_sane_readahead() stuff and
use per-device readahead limit everywhere.
Also, using right readahead size for RAID disks can significantly
increase i/o performance:
before:
dd if=/dev/md2 of=/dev/null bs=100M count=100
100+0 records in
100+0 records out 10485760000 bytes (10 GB) copied, 12.9741 s, 808 MB/s
after:
$ dd if=/dev/md2 of=/dev/null bs=100M count=100
100+0 records in
100+0 records out 10485760000 bytes (10 GB) copied, 8.91317 s, 1.2 GB/s
(It's an 8-disks RAID5 storage).
This patch doesn't change sys_readahead and madvise(MADV_WILLNEED)
behavior introduced by 6d2be915e589b58 ("mm/readahead.c: fix readahead
failure for memoryless NUMA nodes and limit readahead pages").
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: onstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Yaowei Bai [Wed, 21 Oct 2015 22:03:02 +0000 (09:03 +1100)]
mm/page_alloc: remove unused parameter in init_currently_empty_zone()
Commit a2f3aa02576632cdb ("[PATCH] Fix sparsemem on Cell") fixed an oops
experienced on the Cell architecture when init-time functions, early_*(),
are called at runtime by introducing an 'enum memmap_context' parameter to
memmap_init_zone() and init_currently_empty_zone(). This parameter is
intended to be used to tell whether the call of these two functions is
being made on behalf of a hotplug event, or happening at boot-time.
However, init_currently_empty_zone() does not use this parameter at all,
so remove it.
Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vlastimil Babka [Wed, 21 Oct 2015 22:03:01 +0000 (09:03 +1100)]
mm, migrate: count pages failing all retries in vmstat and tracepoint
Migration tries up to 10 times to migrate pages that return -EAGAIN until
it gives up. If some pages fail all retries, they are counted towards the
number of failed pages that migrate_pages() returns. They should also be
counted in the /proc/vmstat pgmigrate_fail and in the mm_migrate_pages
tracepoint.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Raghavendra K T [Wed, 21 Oct 2015 22:02:59 +0000 (09:02 +1100)]
arch/powerpc/mm/numa.c: do not allocate bootmem memory for non existing nodes
With the setup_nr_nodes(), we have already initialized
node_possible_map. So it is safe to use for_each_node here.
There are many places in the kernel that use hardcoded 'for' loop with
nr_node_ids, because all other architectures have numa nodes populated
serially. That should be reason we had maintained the same for
powerpc.
But, since sparse numa node ids possible on powerpc, we unnecessarily
allocate memory for non existent numa nodes.
For e.g., on a system with 0,1,16,17 as numa nodes nr_node_ids=18 and
we allocate memory for nodes 2-14. This patch we allocate memory for
only existing numa nodes.
The patch is boot tested on a 4 node tuleta, confirming with printks
that it works as expected.
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Anton Blanchard <anton@samba.org> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Greg Kurz <gkurz@linux.vnet.ibm.com> Cc: Grant Likely <grant.likely@linaro.org> Cc: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Raghavendra K T [Wed, 21 Oct 2015 22:02:59 +0000 (09:02 +1100)]
mm/list_lru.c: replace nr_node_ids for loop with for_each_node()
The functions used in the patch are in slowpath, which gets called
whenever alloc_super is called during mounts.
Though this should not make difference for the architectures with
sequential numa node ids, for the powerpc which can potentially have
sparse node ids (for e.g., 4 node system having numa ids, 0,1,16,17 is
common), this patch saves some unnecessary allocations for non existing
numa nodes.
Even without that saving, perhaps patch makes code more readable.
[vdavydov@parallels.com: take memcg_aware check outside for_each loop] Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Anton Blanchard <anton@samba.org> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Greg Kurz <gkurz@linux.vnet.ibm.com> Cc: Grant Likely <grant.likely@linaro.org> Cc: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
khugepaged does swap in during collapse under anon_vma lock. It causes
complain from lockdep. The trace below shows following scenario:
- khugepaged tries to swap in a page under mmap_sem and anon_vma lock;
- do_swap_page() calls swapin_readahead() with GFP_HIGHUSER_MOVABLE;
- __read_swap_cache_async() tries to allocate the page for swap in;
- lockdep_trace_alloc() in __alloc_pages_nodemask() notices that with
given gfp_mask we could end up in direct relaim.
- Lockdep already knows that reclaim sometimes (e.g. in case of
split_huge_page()) wants to take anon_vma lock on its own.
Therefore deadlock is possible.
The fix is to take anon_vma lock after swap in.
[18344.236625] =================================
[18344.236628] [ INFO: inconsistent lock state ]
[18344.236633] 4.3.0-rc1-next-20150918-dbg-00014-ge5128d0-dirty #361 Not tainted
[18344.236636] ---------------------------------
[18344.236640] inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
[18344.236645] khugepaged/32 [HC0[0]:SC0[0]:HE1:SE1] takes:
[18344.236648] (&anon_vma->rwsem){++++?.}, at: [<ffffffff81134403>] khugepaged+0x8b0/0x1987
[18344.236662] {IN-RECLAIM_FS-W} state was registered at:
[18344.236666] [<ffffffff8107d747>] __lock_acquire+0x8e2/0x1183
[18344.236673] [<ffffffff8107e7ac>] lock_acquire+0x10b/0x1a6
[18344.236678] [<ffffffff8150a367>] down_write+0x3b/0x6a
[18344.236686] [<ffffffff811360d8>] split_huge_page_to_list+0x5b/0x61f
[18344.236689] [<ffffffff811224b3>] add_to_swap+0x37/0x78
[18344.236691] [<ffffffff810fd650>] shrink_page_list+0x4c2/0xb9a
[18344.236694] [<ffffffff810fe47c>] shrink_inactive_list+0x371/0x5d9
[18344.236696] [<ffffffff810fee2f>] shrink_lruvec+0x410/0x5ae
[18344.236698] [<ffffffff810ff024>] shrink_zone+0x57/0x140
[18344.236700] [<ffffffff810ffc79>] kswapd+0x6a5/0x91b
[18344.236702] [<ffffffff81059588>] kthread+0x107/0x10f
[18344.236706] [<ffffffff8150c7bf>] ret_from_fork+0x3f/0x70
[18344.236708] irq event stamp: 6517947
[18344.236709] hardirqs last enabled at (6517947): [<ffffffff810f2d0c>] get_page_from_freelist+0x362/0x59e
[18344.236713] hardirqs last disabled at (6517946): [<ffffffff8150ba41>] _raw_spin_lock_irqsave+0x18/0x51
[18344.236715] softirqs last enabled at (6507072): [<ffffffff81041cb0>] __do_softirq+0x2df/0x3f5
[18344.236719] softirqs last disabled at (6507055): [<ffffffff81041fb5>] irq_exit+0x40/0x94
[18344.236722]
other info that might help us debug this:
[18344.236723] Possible unsafe locking scenario:
Ebru Akagunduz [Wed, 21 Oct 2015 22:02:58 +0000 (09:02 +1100)]
mm: make swapin readahead to improve thp collapse rate
This patch makes swapin readahead to improve thp collapse rate. When
khugepaged scanned pages, there can be a few of the pages in swap area.
With the patch THP can collapse 4kB pages into a THP when there are up to
max_ptes_swap swap ptes in a 2MB range.
The patch was tested with a test program that allocates 400B of memory,
writes to it, and then sleeps. I force the system to swap out all.
Afterwards, the test program touches the area by writing, it skips a page
in each 20 pages of the area.
Without the patch, system did not swap in readahead. THP rate was %65 of
the program of the memory, it did not change over time.
With this patch, after 10 minutes of waiting khugepaged had collapsed %99
of the program's memory.
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Vladimir Davydov [Wed, 21 Oct 2015 22:02:58 +0000 (09:02 +1100)]
mm/khugepaged: fix scan not aborted on SCAN_EXCEED_SWAP_PTE
This patch fixes a typo in khugepaged_scan_pmd(): instead of setting
"result" to SCAN_EXCEED_SWAP_PTE we set "ret". Setting "ret" results in
an attempt to collapse a huge page although we meant aborting the scan.
As a result, we can call khugepaged_find_target_node() with all entries
in the khugepaged_node_load array being zeros. The latter is not ready
for that and might return an offline node on such input. This leads to a
warning followed by kernel panic:
khugepaged: avoid usage of uninitialized variable 'isolated'
In file included from include/trace/events/huge_memory.h:7:0,
from mm/huge_memory.c:62:
include/linux/tracepoint.h:141:5: warning: `isolated' may be used uninitialized in this function [-Wmaybe-uninitialized]
((void(*)(proto))(it_func))(args); \
^
mm/huge_memory.c:2327:6: note: `isolated' was declared here
int isolated, result = 0;
We make use of isolated in error path before it get initialized.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Ebru Akagunduz [Wed, 21 Oct 2015 22:02:58 +0000 (09:02 +1100)]
mm: make optimistic check for swapin readahead
Introduce a new sysfs integer knob
/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_swap which makes
optimistic check for swapin readahead to increase thp collapse rate.
Before getting swapped out pages to memory, checks them and allows up to a
certain number. It also prints out using tracepoints amount of unmapped
ptes.
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Ebru Akagunduz [Wed, 21 Oct 2015 22:02:57 +0000 (09:02 +1100)]
mm: add tracepoint for scanning pages
This patch series makes swapin readahead up to a certain number to gain
more thp performance and adds tracepoint for khugepaged_scan_pmd,
collapse_huge_page, __collapse_huge_page_isolate.
This patch series was written to deal with programs that access most, but
not all, of their memory after they get swapped out. Currently these
programs do not get their memory collapsed into THPs after the system
swapped their memory out, while they would get THPs before swapping
happened.
This patch series was tested with a test program, it allocates 400MB of
memory, writes to it, and then sleeps. I force the system to swap out
all. Afterwards, the test program touches the area by writing and leaves
a piece of it without writing. This shows how much swap in readahead made
by the patch.
Tejun Heo [Wed, 21 Oct 2015 22:02:57 +0000 (09:02 +1100)]
memcg: drop unnecessary cold-path tests from __memcg_kmem_bypass()
__memcg_kmem_bypass() decides whether a kmem allocation should be bypassed
to the root memcg. Some conditions that it tests are valid criteria
regarding who should be held accountable; however, there are a couple
unnecessary tests for cold paths - __GFP_FAIL and fatal_signal_pending().
The previous patch updated try_charge() to handle both __GFP_FAIL and
dying tasks correctly and the only thing these two tests are doing is
making accounting less accurate and sprinkling tests for cold path
conditions in the hot paths. There's nothing meaningful gained by these
extra tests.
This patch removes the two unnecessary tests from __memcg_kmem_bypass().
Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tejun Heo [Wed, 21 Oct 2015 22:02:57 +0000 (09:02 +1100)]
memcg: ratify and consolidate over-charge handling
try_charge() is the main charging logic of memcg. When it hits the limit
but either can't fail the allocation due to __GFP_NOFAIL or the task is
likely to free memory very soon, being OOM killed, has SIGKILL pending or
exiting, it "bypasses" the charge to the root memcg and returns -EINTR.
While this is one approach which can be taken for these situations, it has
several issues.
* It unnecessarily lies about the reality. The number itself doesn't
go over the limit but the actual usage does. memcg is either forced
to or actively chooses to go over the limit because that is the
right behavior under the circumstances, which is completely fine,
but, if at all avoidable, it shouldn't be misrepresenting what's
happening by sneaking the charges into the root memcg.
* Despite trying, we already do over-charge. kmemcg can't deal with
switching over to the root memcg by the point try_charge() returns
-EINTR, so it open-codes over-charing.
* It complicates the callers. Each try_charge() user has to handle
the weird -EINTR exception. memcg_charge_kmem() does the manual
over-charging. mem_cgroup_do_precharge() performs unnecessary
uncharging of root memcg, which BTW is inconsistent with what
memcg_charge_kmem() does but not broken as [un]charging are noops on
root memcg. mem_cgroup_try_charge() needs to switch the returned
cgroup to the root one.
The reality is that in memcg there are cases where we are forced and/or
willing to go over the limit. Each such case needs to be scrutinized and
justified but there definitely are situations where that is the right
thing to do. We alredy do this but with a superficial and inconsistent
disguise which leads to unnecessary complications.
This patch updates try_charge() so that it over-charges and returns 0 when
deemed necessary. -EINTR return is removed along with all special case
handling in the callers.
While at it, remove the local variable @ret, which was initialized to zero
and never changed, along with done: label which just returned the always
zero @ret.
Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tejun Heo [Wed, 21 Oct 2015 22:02:57 +0000 (09:02 +1100)]
memcg: collect kmem bypass conditions into __memcg_kmem_bypass()
memcg_kmem_newpage_charge() and memcg_kmem_get_cache() are testing the
same series of conditions to decide whether to bypass kmem accounting.
Collect the tests into __memcg_kmem_bypass().
This is pure refactoring.
Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tejun Heo [Wed, 21 Oct 2015 22:02:57 +0000 (09:02 +1100)]
memcg: punt high overage reclaim to return-to-userland path
Currently, try_charge() tries to reclaim memory synchronously when the
high limit is breached; however, if the allocation doesn't have
__GFP_WAIT, synchronous reclaim is skipped. If a process performs only
speculative allocations, it can blow way past the high limit. This is
actually easily reproducible by simply doing "find /". slab/slub
allocator tries speculative allocations first, so as long as there's
memory which can be consumed without blocking, it can keep allocating
memory regardless of the high limit.
This patch makes try_charge() always punt the over-high reclaim to the
return-to-userland path. If try_charge() detects that high limit is
breached, it adds the overage to current->memcg_nr_pages_over_high and
schedules execution of mem_cgroup_handle_over_high() which performs
synchronous reclaim from the return-to-userland path.
As long as kernel doesn't have a run-away allocation spree, this should
provide enough protection while making kmemcg behave more consistently.
It also has the following benefits.
- All over-high reclaims can use GFP_KERNEL regardless of the specific
gfp mask in use, e.g. GFP_NOFS, when the limit was breached.
- It copes with prio inversion. Previously, a low-prio task with
small memory.high might perform over-high reclaim with a bunch of
locks held. If a higher prio task needed any of these locks, it
would have to wait until the low prio task finished reclaim and
released the locks. By handing over-high reclaim to the task exit
path this issue can be avoided.
Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@kernel.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tejun Heo [Wed, 21 Oct 2015 22:02:56 +0000 (09:02 +1100)]
memcg: flatten task_struct->memcg_oom
task_struct->memcg_oom is a sub-struct containing fields which are used
for async memcg oom handling. Most task_struct fields aren't packaged
this way and it can lead to unnecessary alignment paddings. This patch
flattens it.
In addition, task.memcg_may_oom is relocated to where other bitfields are
which reduces the size of task_struct.
Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrew Morton [Wed, 21 Oct 2015 22:02:55 +0000 (09:02 +1100)]
uaccess: reimplement probe_kernel_address() using probe_kernel_read()
probe_kernel_address() is basically the same as the (later added)
probe_kernel_read().
The return value on EFAULT is a bit different: probe_kernel_address()
returns number-of-bytes-not-copied whereas probe_kernel_read() returns
-EFAULT. All callers have been checked, none cared.
probe_kernel_read() can be overridden by the architecture whereas
probe_kernel_address() cannot. parisc, blackfin and um do this, to insert
additional checking. Hence this patch possibly fixes obscure bugs,
although there are only two probe_kernel_address() callsites outside
arch/.
My first attempt involved removing probe_kernel_address() entirely and
converting all callsites to use probe_kernel_read() directly, but that got
tiresome.
This patch shrinks mm/slab_common.o by 218 bytes. For a single
probe_kernel_address() callsite.
Cc: Steven Miao <realmz6@gmail.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jiang Liu [Wed, 21 Oct 2015 22:02:55 +0000 (09:02 +1100)]
mm: update _mem_id_[] for every possible CPU when memory configuration changes
Current kernel only updates _mem_id_[cpu] for onlined CPUs when memory
configuration changes. So kernel may allocate memory from remote node for
a CPU if the CPU is still in absent or offline state even if the node
associated with the CPU has already been onlined. This patch tries to
improve performance by updating _mem_id_[cpu] for each possible CPU when
memory configuration changes, thus kernel could always allocate from local
node once the node is onlined.
We check node_online(cpu_to_node(cpu)) because:
1) local_memory_node(nid) needs to access NODE_DATA(nid)
2) try_offline_node(nid) just zeroes out NODE_DATA(nid) instead of free it
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jiang Liu [Wed, 21 Oct 2015 22:02:55 +0000 (09:02 +1100)]
x86, numa: kill useless code to improve code readability
According to x86 boot sequence, early_cpu_to_node() always returns
NUMA_NO_NODE when called from numa_init(). So kill useless code to
improve code readability.
Related code sequence as below:
x86_cpu_to_node_map is set until step 2, so it is still the default
value (NUMA_NO_NODE) when accessed at step 1.
Jiang Liu [Wed, 21 Oct 2015 22:02:55 +0000 (09:02 +1100)]
openvswitch: replace cpu_to_node() with cpu_to_mem() to support memoryless node
ovs_flow_stats_update() allocates memory with __GFP_THISNODE flag set,
which may cause permanent memory allocation failure on memoryless node.
So replace cpu_to_node() with cpu_to_mem() to better support memoryless
node. For node with memory, cpu_to_mem() is the same as cpu_to_node().
This change only affects performance and shouldn't affect functionality.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> Acked-by: Pravin B Shelar <pshelar@nicira.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jiang Liu [Wed, 21 Oct 2015 22:02:55 +0000 (09:02 +1100)]
sgi-xp: replace cpu_to_node() with cpu_to_mem() to support memoryless node
xpc_create_gru_mq_uv() allocates memory with __GFP_THISNODE flag set,
which may cause permanent memory allocation failure on memoryless node.
So replace cpu_to_node() with cpu_to_mem() to better support memoryless
node. For node with memory, cpu_to_mem() is the same as cpu_to_node().
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jiang Liu [Wed, 21 Oct 2015 22:02:54 +0000 (09:02 +1100)]
kernel/profile.c: replace cpu_to_mem() with cpu_to_node()
Function profile_cpu_callback() allocates memory without specifying
__GFP_THISNODE flag, so replace cpu_to_mem() with cpu_to_node() because
cpu_to_mem() may cause suboptimal memory allocation if there's no free
memory on the node returned by cpu_to_mem().
It's safe to use cpu_to_mem() because build_all_zonelists() also builds
suitable fallback zonelist for memoryless node.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jiang Liu [Wed, 21 Oct 2015 22:02:54 +0000 (09:02 +1100)]
x86, NUMA, ACPI: online node earlier when doing CPU hot-addition
This is the third version to enable memoryless node support on x86
platforms. The previous version (https://lkml.org/lkml/2014/7/11/75)
blindly replaces numa_node_id()/cpu_to_node() with numa_mem_id()/
cpu_to_mem(). That's not the right solution as pointed out by Tejun and
Peter due to:
1) We shouldn't shift the burden to normal slab users.
2) Details of memoryless node should be hidden in arch and mm code
as much as possible.
After digging into more code and documentation, we found the rules to
deal with memoryless node should be:
1) Arch code should online corresponding NUMA node before onlining any
CPU or memory, otherwise it may cause invalid memory access when
accessing NODE_DATA(nid).
2) For normal memory allocations without __GFP_THISNODE setting in the
gfp_flags, we should prefer numa_node_id()/cpu_to_node() instead of
numa_mem_id()/cpu_to_mem() because the latter loses hardware topology
information as pointed out by Tejun:
A - B - X - C - D
Where X is the memless node. numa_mem_id() on X would return
either B or C, right? If B or C can't satisfy the allocation,
the allocator would fallback to A from B and D for C, both of
which aren't optimal. It should first fall back to C or B
respectively, which the allocator can't do anymoe because the
information is lost when the caller side performs numa_mem_id().
3) For memory allocation with __GFP_THISNODE setting in gfp_flags,
numa_node_id()/cpu_to_node() should be used if caller only wants to
allocate from local memory, otherwise numa_mem_id()/cpu_to_mem()
should be used if caller wants to allocate from the nearest node
with memory.
4) numa_mem_id()/cpu_to_mem() should be used if caller wants to check
whether a page is allocated from the nearest node.
Based on above rules, this patch set
1) Patch 1 is a bugfix to resolve a crash caused by socket hot-addition
2) Patch 2 replaces numa_mem_id() with numa_node_id() when __GFP_THISNODE
isn't set in gfp_flags.
3) Patch 3-6 replaces numa_node_id()/cpu_to_node() with numa_mem_id()/
cpu_to_mem() if caller wants to allocate from local node only.
4) Patch 7-9 enables support of memoryless node on x86.
With this patch set applied, on a system with two sockets enabled at boot,
one with memory and the other without memory, we got following numa
topology after boot:
root@bkd04sdp:~# numactl --hardware
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
node 0 size: 15940 MB
node 0 free: 15397 MB
node 1 cpus: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59
node 1 size: 0 MB
node 1 free: 0 MB
node distances:
node 0 1
0: 10 21
1: 21 10
With typical CPU hot-addition flow on x86, PCI host bridges embedded
in physical processor are always associated with NOMA_NO_NODE, which
may cause sub-optimal performance.
So associated node is always in offline state because it is onlined
until step 3.a or 4.a.
We could improve performance by online node at step 1.a. This change also
makes the code symmetric. Nodes are always created when handling
CPU/memory hot-addition events instead of handling user requests from
sysfs interfaces, and are destroyed when handling CPU/memory hot-removal
events.
Wei Yang [Wed, 21 Oct 2015 22:02:54 +0000 (09:02 +1100)]
mm/slub: calculate start order with reserved in consideration
In slub_order(), the order starts from max(min_order,
get_order(min_objects * size)). When (min_objects * size) has different
order from (min_objects * size + reserved), it will skip this order via a
check in the loop.
This patch optimizes this a little by calculating the start order with
`reserved' in consideration and removing the check in loop.
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Wei Yang [Wed, 21 Oct 2015 22:02:53 +0000 (09:02 +1100)]
mm/slub: use get_order() instead of fls()
get_order() is more easy to understand.
This patch just replaces it.
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Wei Yang [Wed, 21 Oct 2015 22:02:53 +0000 (09:02 +1100)]
mm/slub: correct the comment in calculate_order()
In calculate_order(), it tries to calculate the best order by adjusting
the fraction and min_objects. On each iteration on min_objects, fraction
iterates on 16, 8, 4. Which means the acceptable waste increases with
1/16, 1/8, 1/4.
This patch corrects the comment according to the code.
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alexandru Moise [Wed, 21 Oct 2015 22:02:53 +0000 (09:02 +1100)]
mm/slab_common.c: initialize kmem_cache pointer to NULL
The assignment to NULL within the error condition was written in a 2014
patch to suppress a compiler warning. However it would be cleaner to just
initialize the kmem_cache to NULL and just return it in case of an error
condition.
Signed-off-by: Alexandru Moise <00moses.alexander00@gmail.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
GNUplot `slabinfo -X' stats, collected, for example, using the
following command:
while [ 1 ]; do slabinfo -X >> stats; sleep 1; done
`slabinfo-gnuplot.sh stats' pre-processes collected records
and generate graphs (totals, slabs sorted by size, slabs
sorted by size).
Graphs can be [individually] regenerate with different samples
range and graph width-heigh (-r %d,%d and -s %d,%d options).
To visually compare N `totals' graphs:
slabinfo-gnuplot.sh -t FILE1-totals FILE2-totals ... FILEN-totals
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
checkpatch.pl complains about globals being explicitly zeroed
out: "ERROR: do not initialise globals to 0 or NULL".
New globals, introduced in this patch set, have no explicit 0
initialization; clean up the old ones to make it less hairy.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
projects / karo-tx-linux.git / log