Mel Gorman [Fri, 7 Jun 2013 00:07:40 +0000 (10:07 +1000)]
mm: vmscan: flatten kswapd priority loop
kswapd stops raising the scanning priority when at least SWAP_CLUSTER_MAX
pages have been reclaimed or the pgdat is considered balanced. It then
rechecks if it needs to restart at DEF_PRIORITY and whether high-order
reclaim needs to be reset. This is not wrong per-se but it is confusing
to follow and forcing kswapd to stay at DEF_PRIORITY may require several
restarts before it has scanned enough pages to meet the high watermark
even at 100% efficiency. This patch irons out the logic a bit by
controlling when priority is raised and removing the "goto loop_again".
This patch has kswapd raise the scanning priority until it is scanning
enough pages that it could meet the high watermark in one shrink of the
LRU lists if it is able to reclaim at 100% efficiency. It will not raise
the scanning prioirty higher unless it is failing to reclaim any pages.
To avoid infinite looping for high-order allocation requests kswapd will
not reclaim for high-order allocations when it has reclaimed at least
twice the number of pages as the allocation request.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Fri, 7 Jun 2013 00:07:40 +0000 (10:07 +1000)]
mm: vmscan: obey proportional scanning requirements for kswapd
Simplistically, the anon and file LRU lists are scanned proportionally
depending on the value of vm.swappiness although there are other factors
taken into account by get_scan_count(). The patch "mm: vmscan: Limit the
number of pages kswapd reclaims" limits the number of pages kswapd
reclaims but it breaks this proportional scanning and may evenly shrink
anon/file LRUs regardless of vm.swappiness.
This patch preserves the proportional scanning and reclaim. It does mean
that kswapd will reclaim more than requested but the number of pages will
be related to the high watermark.
[mhocko@suse.cz: Correct proportional reclaim for memcg and simplify]
[kamezawa.hiroyu@jp.fujitsu.com: Recalculate scan based on target]
[hannes@cmpxchg.org: Account for already scanned pages properly] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Mel Gorman [Fri, 7 Jun 2013 00:07:39 +0000 (10:07 +1000)]
mm: vmscan: limit the number of pages kswapd reclaims at each priority
This series does not fix all the current known problems with reclaim but
it addresses one important swapping bug when there is background IO.
Changelog since V3
o Drop the slab shrink changes in light of Glaubers series and
discussions highlighted that there were a number of potential
problems with the patch. (mel)
o Rebased to 3.10-rc1
Changelog since V2
o Preserve ratio properly for proportional scanning (kamezawa)
Changelog since V1
o Rename ZONE_DIRTY to ZONE_TAIL_LRU_DIRTY (andi)
o Reformat comment in shrink_page_list (andi)
o Clarify some comments (dhillf)
o Rework how the proportional scanning is preserved
o Add PageReclaim check before kswapd starts writeback
o Reset sc.nr_reclaimed on every full zone scan
Kswapd and page reclaim behaviour has been screwy in one way or the other
for a long time. Very broadly speaking it worked in the far past because
machines were limited in memory so it did not have that many pages to scan
and it stalled congestion_wait() frequently to prevent it going completely
nuts. In recent times it has behaved very unsatisfactorily with some of
the problems compounded by the removal of stall logic and the introduction
of transparent hugepage support with high-order reclaims.
There are many variations of bugs that are rooted in this area. One
example is reports of a large copy operations or backup causing the
machine to grind to a halt or applications pushed to swap. Sometimes in
low memory situations a large percentage of memory suddenly gets
reclaimed. In other cases an application starts and kswapd hits 100% CPU
usage for prolonged periods of time and so on. There is now talk of
introducing features like an extra free kbytes tunable to work around
aspects of the problem instead of trying to deal with it. It's compounded
by the problem that it can be very workload and machine specific.
This series aims at addressing some of the worst of these problems without
attempting to fundmentally alter how page reclaim works.
Patches 1-2 limits the number of pages kswapd reclaims while still obeying
the anon/file proportion of the LRUs it should be scanning.
Patches 3-4 control how and when kswapd raises its scanning priority and
deletes the scanning restart logic which is tricky to follow.
Patch 5 notes that it is too easy for kswapd to reach priority 0 when
scanning and then reclaim the world. Down with that sort of thing.
Patch 6 notes that kswapd starts writeback based on scanning priority which
is not necessarily related to dirty pages. It will have kswapd
writeback pages if a number of unqueued dirty pages have been
recently encountered at the tail of the LRU.
Patch 7 notes that sometimes kswapd should stall waiting on IO to complete
to reduce LRU churn and the likelihood that it'll reclaim young
clean pages or push applications to swap. It will cause kswapd
to block on IO if it detects that pages being reclaimed under
writeback are recycling through the LRU before the IO completes.
Patchies 8-9 are cosmetic but balance_pgdat() is easier to follow after they
are applied.
This was tested using memcached+memcachetest while some background IO was
in progress as implemented by the parallel IO tests implement in MM Tests.
memcachetest benchmarks how many operations/second memcached can service
and it is run multiple times. It starts with no background IO and then
re-runs the test with larger amounts of IO in the background to roughly
simulate a large copy in progress. The expectation is that the IO should
have little or no impact on memcachetest which is running entirely in
memory.
Note how the vanilla kernels performance collapses when there is enough IO
taking place in the background. This drop in performance is part of what
users complain of when they start backups. Note how the swapin and major
fault figures indicate that processes were being pushed to swap
prematurely. With the series applied, there is no noticable performance
drop and while there is still some swap activity, it's tiny.
20 iterations of this test were run in total and averaged. Every 5
iterations, additional IO was generated in the background using dd to
measure how the workload was impacted. The 0M, 715M, 2385M and 4055M
subblock refer to the amount of IO going on in the background at each
iteration. So memcachetest-2385M is reporting how many
transactions/second memcachetest recorded on average over 5 iterations
while there was 2385M of IO going on in the ground. There are six blocks
of information reported here
memcachetest is the transactions/second reported by memcachetest. In
the vanilla kernel note that performance drops from around
22K/sec to just under 4K/second when there is 2385M of IO going
on in the background. This is one type of performance collapse
users complain about if a large cp or backup starts in the
background
io-duration refers to how long it takes for the background IO to
complete. It's showing that with the patched kernel that the IO
completes faster while not interfering with the memcache
workload
swaptotal is the total amount of swap traffic. With the patched kernel,
the total amount of swapping is much reduced although it is
still not zero.
swapin in this case is an indication as to whether we are swap trashing.
The closer the swapin/swapout ratio is to 1, the worse the
trashing is. Note with the patched kernel that there is no swapin
activity indicating that all the pages swapped were really inactive
unused pages.
minorfaults are just minor faults. An increased number of minor faults
can indicate that page reclaim is unmapping the pages but not
swapping them out before they are faulted back in. With the
patched kernel, there is only a small change in minor faults
majorfaults are just major faults in the target workload and a high
number can indicate that a workload is being prematurely
swapped. With the patched kernel, major faults are much reduced. As
there are no swapin's recorded so it's not being swapped. The likely
explanation is that that libraries or configuration files used by
the workload during startup get paged out by the background IO.
Overall with the series applied, there is no noticable performance drop
due to background IO and while there is still some swap activity, it's
tiny and the lack of swapins imply that the swapped pages were inactive
and unused.
Unfortunately, note that there is a small amount of direct reclaim due to
kswapd no longer reclaiming the world. ftrace indicates that the direct
reclaim stalls are mostly harmless with the vast bulk of the stalls
incurred by dd
A consequence of the direct reclaim for dd is that the processes for the
IO workload may show a higher system CPU usage. There is also a risk that
kswapd not reclaiming the world may mean that it stays awake balancing
zones, does not stall on the appropriate events and continually scans
pages it cannot reclaim consuming CPU. This will be visible as continued
high CPU usage but in my own tests I only saw a single spike lasting less
than a second and I did not observe any problems related to reclaim while
running the series on my desktop.
This patch:
The number of pages kswapd can reclaim is bound by the number of pages it
scans which is related to the size of the zone and the scanning priority.
In many cases the priority remains low because it's reset every
SWAP_CLUSTER_MAX reclaimed pages but in the event kswapd scans a large
number of pages it cannot reclaim, it will raise the priority and
potentially discard a large percentage of the zone as sc->nr_to_reclaim is
ULONG_MAX. The user-visible effect is a reclaim "spike" where a large
percentage of memory is suddenly freed. It would be bad enough if this
was just unused memory but because of how anon/file pages are balanced it
is possible that applications get pushed to swap unnecessarily.
This patch limits the number of pages kswapd will reclaim to the high
watermark. Reclaim will still overshoot due to it not being a hard limit
as shrink_lruvec() will ignore the sc.nr_to_reclaim at DEF_PRIORITY but it
prevents kswapd reclaiming the world at higher priorities. The number of
pages it reclaims is not adjusted for high-order allocations as kswapd
will reclaim excessively if it is to balance zones for high-order
allocations.
Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Tested-by: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/THP: deposit the transpare huge pgtable before set_pmd
Architectures like powerpc use the deposited pgtable to store hash index
values. We need to make the deposted pgtable is visible to other cpus
before we are ready to take a hash fault.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/THP: don't use HPAGE_SHIFT in transparent hugepage code
For architectures like powerpc that support multiple explicit hugepage
sizes, HPAGE_SHIFT indicate the default explicit hugepage shift. For THP
to work the hugepage size should be same as PMD_SIZE. So use PMD_SHIFT
directly. So move the define outside CONFIG_TRANSPARENT_HUGEPAGE #ifdef
because we want to use these defines in generic code with if
(pmd_trans_huge()) conditional.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/THP: withdraw the pgtable after pmdp related operations
For architectures like ppc64 we look at deposited pgtable when calling
pmdp_get_and_clear. So do the pgtable_trans_huge_withdraw after finishing
pmdp related operations.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/THP: add pmd args to pgtable deposit and withdraw APIs
This will be later used by powerpc THP support. In powerpc we want to use
pgtable for storing the hash index values. So instead of adding them to
mm_context list, we would like to store them in the second half of pmd
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/thp: use the correct function when updating access flags
We should use pmdp_set_access_flags to update access flags. Archs like
powerpc use extra checks(_PAGE_BUSY) when updating a hugepage PTE. A
set_pmd_at doesn't do those checks. We should use set_pmd_at only when
updating a none hugepage PTE.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com>a Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cody P Schafer [Fri, 7 Jun 2013 00:07:37 +0000 (10:07 +1000)]
mm/page_alloc: in zone_pcp_update(), uze zone_pageset_init()
Previously, zone_pcp_update() called pageset_set_batch() directly,
essentially assuming that percpu_pagelist_fraction == 0. Correct this by
calling zone_pageset_init(), which chooses the appropriate ->batch and
->high calculations.
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cody P Schafer [Fri, 7 Jun 2013 00:07:36 +0000 (10:07 +1000)]
mm/page_alloc: convert zone_pcp_update() to rely on memory barriers instead of stop_machine()
zone_pcp_update()'s goal is to adjust the ->high and ->mark members of a
percpu pageset based on a zone's ->managed_pages. We don't need to drain
the entire percpu pageset just to modify these fields.
This lets us avoid calling setup_pageset() (and the draining required to
call it) and instead allows simply setting the fields' values (with some
attention paid to memory barriers to prevent the relationship between
->batch and ->high from being thrown off).
This does change the behavior of zone_pcp_update() as the percpu pagesets
will not be drained when zone_pcp_update() is called (they will end up
being shrunk, not completely drained, later when a 0-order page is freed
in free_hot_cold_page()).
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cody P Schafer [Fri, 7 Jun 2013 00:07:35 +0000 (10:07 +1000)]
mm/page_alloc: insert memory barriers to allow async update of pcp batch and high
Introduce pageset_update() to perform a safe transision from one set of
pcp->{batch,high} to a new set using memory barriers.
This ensures that batch is always set to a safe value (1) prior to
updating high, and ensure that high is fully updated before setting the
real value of batch. It avoids ->batch ever rising above ->high.
Cody P Schafer [Fri, 7 Jun 2013 00:07:35 +0000 (10:07 +1000)]
mm/page_alloc: prevent concurrent updaters of pcp ->batch and ->high
Because we are going to rely upon a careful transision between old and new
->high and ->batch values using memory barriers and will remove
stop_machine(), we need to prevent multiple updaters from interweaving
their memory writes.
Add a simple mutex to protect both update loops.
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cody P Schafer [Fri, 7 Jun 2013 00:07:34 +0000 (10:07 +1000)]
mm/page_alloc: factor out setting of pcp->high and pcp->batch
"Problems" with the current code:
1: there is a lack of synchronization in setting ->high and ->batch in
percpu_pagelist_fraction_sysctl_handler()
2: stop_machine() in zone_pcp_update() is unnecissary.
3: zone_pcp_update() does not consider the case where
percpu_pagelist_fraction is non-zero
To fix:
1: add memory barriers, a safe ->batch value, an update side mutex when
updating ->high and ->batch, and use ACCESS_ONCE() for ->batch users
that expect a stable value.
2: avoid draining pages in zone_pcp_update(), rely upon the memory
barriers added to fix #1
3: factor out quite a few functions, and then call the appropriate one.
Note that it results in a change to the behavior of zone_pcp_update(),
which is used by memory_hotplug. I'm rather certain that I've diserned
(and preserved) the essential behavior (changing ->high and ->batch), and
only eliminated unneeded actions (draining the per cpu pages), but this
may not be the case.
Further note that the draining of pages that previously took place in
zone_pcp_update() occured after repeated draining when attempting to
offline a page, and after the offline has "succeeded". It appears that
the draining was added to zone_pcp_update() to avoid refactoring
setup_pageset() into 2 funtions.
This patch:
Creates pageset_set_batch() for use in setup_pageset().
pageset_set_batch() imitates the functionality of
setup_pagelist_highmark(), but uses the boot time
(percpu_pagelist_fraction == 0) calculations for determining ->high based
on ->batch.
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Shaohua Li [Fri, 7 Jun 2013 00:07:33 +0000 (10:07 +1000)]
swap: add a simple detector for inappropriate swapin readahead
This is a patch to improve swap readahead algorithm. It's from Hugh and I
slightly changed it.
Hugh's original changelog:
swapin readahead does a blind readahead, whether or not the swapin
is sequential. This may be ok on harddisk, because large reads have
relatively small costs, and if the readahead pages are unneeded they
can be reclaimed easily - though, what if their allocation forced
reclaim of useful pages? But on SSD devices large reads are more
expensive than small ones: if the readahead pages are unneeded,
reading them in caused significant overhead.
This patch adds very simplistic random read detection. Stealing
the PageReadahead technique from Konstantin Khlebnikov's patch,
avoiding the vma/anon_vma sophistications of Shaohua Li's patch,
swapin_nr_pages() simply looks at readahead's current success
rate, and narrows or widens its readahead window accordingly.
There is little science to its heuristic: it's about as stupid
as can be whilst remaining effective.
The table below shows elapsed times (in centiseconds) when running
a single repetitive swapping load across a 1000MB mapping in 900MB
ram with 1GB swap (the harddisk tests had taken painfully too long
when I used mem=500M, but SSD shows similar results for that).
Vanilla is the 3.6-rc7 kernel on which I started; Shaohua denotes
his Sep 3 patch in mmotm and linux-next; HughOld denotes my Oct 1
patch which Shaohua showed to be defective; HughNew this Nov 14
patch, with page_cluster as usual at default of 3 (8-page reads);
HughPC4 this same patch with page_cluster 4 (16-page reads);
HughPC0 with page_cluster 0 (1-page reads: no readahead).
HDD for swapping to harddisk, SSD for swapping to VertexII SSD.
Seq for sequential access to the mapping, cycling five times around;
Rand for the same number of random touches. Anon for a MAP_PRIVATE
anon mapping; Shmem for a MAP_SHARED anon mapping, equivalent to tmpfs.
One weakness of Shaohua's vma/anon_vma approach was that it did
not optimize Shmem: seen below. Konstantin's approach was perhaps
mistuned, 50% slower on Seq: did not compete and is not shown below.
These tests are, of course, two extremes of a very simple case:
under heavier mixed loads I've not yet observed any consistent
improvement or degradation, and wider testing would be welcome.
Shaohua Li:
Test shows Vanilla is slightly better in sequential workload than Hugh's patch.
I observed with Hugh's patch sometimes the readahead size is shrinked too fast
(from 8 to 1 immediately) in sequential workload if there is no hit. And in
such case, continuing doing readahead is good actually.
I don't prepare a sophisticated algorithm for the sequential workload because
so far we can't guarantee sequential accessed pages are swap out sequentially.
So I slightly change Hugh's heuristic - don't shrink readahead size too fast.
Here is my test result (unit second, 3 runs average):
Vanilla Hugh New
Seq 356 370 360
Random 4525 2447 2444
Attached graph is the swapin/swapout throughput I collected with 'vmstat 2'.
The first part is running a random workload (till around 1200 of the x-axis)
and the second part is running a sequential workload. swapin and swapout
throughput are almost identical in steady state in both workloads. These are
expected behavior. while in Vanilla, swapin is much bigger than swapout
especially in random workload (because wrong readahead).
Original patches by: Shaohua Li and Konstantin Khlebnikov.
Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Minchan Kim [Fri, 7 Jun 2013 00:07:33 +0000 (10:07 +1000)]
mm: remove compressed copy from zram in-memory
Swap subsystem does lazy swap slot free with expecting the page would be
swapped out again so we can avoid unnecessary write.
But the problem in in-memory swap(ex, zram) is that it consumes memory
space until vm_swap_full(ie, used half of all of swap device) condition
meet. It could be bad if we use multiple swap device, small in-memory
swap and big storage swap or in-memory swap alone.
This patch makes swap subsystem free swap slot as soon as swap-read is
completed and make the swapcache page dirty so the page should be written
out the swap device to reclaim it. It means we never lose it.
I tested this patch with kernel compile workload.
1. before
compile time : 9882.42
zram max wasted space by fragmentation: 13471881 byte
memory space consumed by zram: 174227456 byte
the number of slot free notify: 206684
2. after
compile time : 9653.90
zram max wasted space by fragmentation: 11805932 byte
memory space consumed by zram: 154001408 byte
the number of slot free notify: 426972
David Rientjes [Fri, 7 Jun 2013 00:07:32 +0000 (10:07 +1000)]
mm, memcg: don't take task_lock in task_in_mem_cgroup
For processes that have detached their mm's, task_in_mem_cgroup()
unnecessarily takes task_lock() when rcu_read_lock() is all that is
necessary to call mem_cgroup_from_task().
While we're here, switch task_in_mem_cgroup() to return bool.
Signed-off-by: David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pavel Emelyanov [Fri, 7 Jun 2013 00:07:32 +0000 (10:07 +1000)]
pagemap: prepare to reuse constant bits with page-shift
In order to reuse bits from pagemap entries gracefully, we leave the
entries as is but on pagemap open emit a warning in dmesg, that bits 55-60
are about to change in a couple of releases. Next, if a user issues
soft-dirty clear command via the clear_refs file (it was disabled before
v3.9) we assume that he's aware of the new pagemap format, note that fact
and report the bits in pagemap in the new manner.
The "migration strategy" looks like this then:
1. existing users are not affected -- they don't touch soft-dirty feature, thus
see old bits in pagemap, but are warned and have time to fix themselves
2. those who use soft-dirty know about new pagemap format
3. some time soon we get rid of any signs of page-shift in pagemap as well as
this trick with clear-soft-dirty affecting pagemap format.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pavel Emelyanov [Fri, 7 Jun 2013 00:07:31 +0000 (10:07 +1000)]
soft-dirty: call mmu notifiers when write-protecting ptes
As noticed by Xiao, since soft-dirty clear command modifies page tables we
have to flush tlbs and call mmu notifiers. While the former is done by
the clear_refs engine itself, the latter is to be done.
One thing to note about this -- in order not to call per-page invalidate
notifier (_all_ address space is about to be changed), the
_invalidate_range_start and _end are used. But for those start and end
are not known exactly. To address this, the same trick as in exit_mmap()
is used -- start is 0 and end is (unsigned long)-1.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pavel Emelyanov [Fri, 7 Jun 2013 00:07:31 +0000 (10:07 +1000)]
mm: soft-dirty bits for user memory changes tracking
The soft-dirty is a bit on a PTE which helps to track which pages a task
writes to. In order to do this tracking one should
1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs)
2. Wait some time.
3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries)
To do this tracking, the writable bit is cleared from PTEs when the
soft-dirty bit is. Thus, after this, when the task tries to modify a page
at some virtual address the #PF occurs and the kernel sets the soft-dirty
bit on the respective PTE.
Note, that although all the task's address space is marked as r/o after the
soft-dirty bits clear, the #PF-s that occur after that are processed fast.
This is so, since the pages are still mapped to physical memory, and thus
all the kernel does is finds this fact out and puts back writable, dirty
and soft-dirty bits on the PTE.
Another thing to note, is that when mremap moves PTEs they are marked with
soft-dirty as well, since from the user perspective mremap modifies the
virtual memory at mremap's new address.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pavel Emelyanov [Fri, 7 Jun 2013 00:07:30 +0000 (10:07 +1000)]
pagemap: introduce pagemap_entry_t without pmshift bits
These bits are always constant (== PAGE_SHIFT) and just occupy space in
the entry. Moreover, in next patch we will need to report one more bit in
the pagemap, but all bits are already busy on it.
That said, describe the pagemap entry that has 6 more free zero bits.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This is the implementation of the soft-dirty bit concept that should help
keep track of changes in user memory, which in turn is very-very required
by the checkpoint-restore project (http://criu.org).
To create a dump of an application(s) we save all the information about it
to files, and the biggest part of such dump is the contents of tasks' memory.
However, there are usage scenarios where it's not required to get _all_ the
task memory while creating a dump. For example, when doing periodical dumps,
it's only required to take full memory dump only at the first step and then
take incremental changes of memory. Another example is live migration. We
copy all the memory to the destination node without stopping all tasks, then
stop them, check for what pages has changed, dump it and the rest of the state,
then copy it to the destination node. This decreases freeze time significantly.
That said, some help from kernel to watch how processes modify the contents
of their memory is required.
The proposal is to track changes with the help of new soft-dirty bit this way:
1. First do "echo 4 > /proc/$pid/clear_refs".
At that point kernel clears the soft dirty _and_ the writable bits from all
ptes of process $pid. From now on every write to any page will result in #pf
and the subsequent call to pte_mkdirty/pmd_mkdirty, which in turn will set
the soft dirty flag.
2. Then read the /proc/$pid/pagemap2 and check the soft-dirty bit reported there
(the 55'th one). If set, the respective pte was written to since last call
to clear refs.
The soft-dirty bit is the _PAGE_BIT_HIDDEN one. Although it's used by kmemcheck,
the latter one marks kernel pages with it, while the former bit is put on user
pages so they do not conflict to each other.
This patch:
A new clear-refs type will be added in the next patch, so prepare
code for that.
[akpm@linux-foundation.org: don't assume that sizeof(enum clear_refs_types) == sizeof(int)] Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sasha Levin [Fri, 7 Jun 2013 00:07:29 +0000 (10:07 +1000)]
watchdog: trigger all-cpu backtrace when locked up and going to panic
Send an NMI to all CPUs when a lockup is detected and the lockup watchdog
code is configured to panic. This gives us a fairly uptodate snapshot of
all CPUs in the system.
This lets us get stack trace of all CPUs which makes life easier trying to
debug a deadlock, and the NMI doesn't change anything since the next step
is a kernel panic.
Josh Hunt [Fri, 7 Jun 2013 00:07:29 +0000 (10:07 +1000)]
block: restore /proc/partitions to not display non-partitionable removable devices
We found with newer kernels we started seeing the cdrom device showing
up in /proc/partitions, but it was not there before.
Looking into this I found that commit d27769ec ("block: add
GENHD_FL_NO_PART_SCAN") introduces this change in behavior. It's not
clear to me from the commit's changelog if this change was intentional or
not. This comment still remains: /* Don't show non-partitionable
removeable devices or empty devices */ so I've decided to send a patch to
restore the behavior of not printing unpartitionable removable devices.
Signed-off-by: Josh Hunt <johunt@akamai.com> Cc: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In line 2908 we can find the copy_to_user function:
2908 if (!ret && copy_to_user(arg, cgc->buffer, blocksize))
The cgc->buffer is never cleaned and initialized before this function. If
ret = 0 with the previous basic block, it's possible to display some
memory bytes in kernel space from userspace.
When we read a block from the disk it normally fills the ->buffer but if
the drive is malfunctioning there is a chance that it would only be
partially filled. The result is an leak information to userspace.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
lglock: update lockdep annotations to report recursive local locks
Oleg Nesterov recently noticed that the lockdep annotations in lglock.c
are not sufficient to detect some obvious deadlocks, such as
lg_local_lock(LOCK) + lg_local_lock(LOCK) or spin_lock(X) +
lg_local_lock(Y) vs lg_local_lock(Y) + spin_lock(X).
Both issues are easily fixed by indicating to lockdep that lglock's local
locks are not recursive. We shouldn't use the rwlock acquire/release
functions here, as lglock doesn't share the same semantics. Instead we
can base our lockdep annotations on the lock_acquire_shared (for local
lglock) and lock_acquire_exclusive (for global lglock) helpers.
I am not proposing new lglock specific helpers as I don't see the point of
the existing second level of helpers :)
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@linux.intel.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In lockdep.h, the spinlock/mutex/rwsem/rwlock/lock_map acquire macros have
different definitions based on the value of CONFIG_PROVE_LOCKING. We have
separate ifdefs for each of these definitions, which seems redundant.
Introduce lock_acquire_{exclusive,shared,shared_recursive} helpers which
will have different definitions based on CONFIG_PROVE_LOCKING. Then all
other helper macros can be defined based on the above ones, which reduces
the amount of ifdefined code.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@linux.intel.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Xue jiufei [Fri, 7 Jun 2013 00:07:24 +0000 (10:07 +1000)]
ocfs2: add missing dlm_put() in dlm_begin_reco_handler()
dlm_begin_reco_handler() returns without putting dlm when dlm recovery
state is DLM_RECO_STATE_FINALIZE.
Signed-off-by: joyce <xuejiufei@huawei.com> Reviewed-by: Jie Liu <jeff.liu@oracle.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Joseph Qi [Fri, 7 Jun 2013 00:07:24 +0000 (10:07 +1000)]
ocfs2: should not use le32_add_cpu to set ocfs2_dinode i_flags
If we use le32_add_cpu to set ocfs2_dinode i_flags, it may lead to the
corresponding flag corrupted. So we should change it to bitwise and/or
operation.
Signed-off-by: Joseph Qi <joseph.qi@huawei.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: shencanquan <shencanquan@huawei.com> Reviewed-by: Jie Liu <jeff.liu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Joseph Qi [Fri, 7 Jun 2013 00:07:23 +0000 (10:07 +1000)]
fs/ocfs2/dlm/dlmrecovery.c:dlm_request_all_locks(): ret should be int instead of enum
In dlm_request_all_locks, ret is type enum. But o2net_send_message
returns a type int value. Then it will never run into the following error
branch. So we should change the ret type from enum to int.
Signed-off-by: Joseph Qi <joseph.qi@huawei.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Acked-by: Sunil Mushran <sunil.mushran@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Below 3 functions have already been declared in dlmcommon.h, so we have
no need to declare them again in dlmrecovery.c.
dlm_complete_recovery_thread
dlm_launch_recovery_thread
dlm_kick_recovery_thread
Signed-off-by: Joseph Qi <joseph.qi@huawei.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Acked-by: Sunil Mushran <sunil.mushran@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jeff Mahoney [Fri, 7 Jun 2013 00:07:22 +0000 (10:07 +1000)]
mISDN: add support for group membership check
This patch adds a module parameter to allow a group access to the mISDN
devices. Otherwise, unpriviledged users on systems with ISDN hardware
have the ability to dial out, potentially causing expensive bills.
Based on a different implementation by Patrick Koppen.
Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Jeff Mahoney <jeffm@suse.com> Cc: Patrick Koppen <isdn4linux@koppen.de> Cc: Karsten Keil <isdn@linux-pingi.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Olaf Hering [Fri, 7 Jun 2013 00:07:22 +0000 (10:07 +1000)]
drivers/net/ethernet/ibm/ehea/ehea_main.c: add alias entry for portN properties
Use separate table for alias entries in the ehea module, otherwise the
probe() function will operate on the separate ports instead of the
lhea-"root" entry of the device-tree
Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Olaf Hering <ohering@suse.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dan Carpenter [Fri, 7 Jun 2013 00:07:21 +0000 (10:07 +1000)]
configfs: use capped length for ->store_attribute()
The difference between "count" and "len" is that "len" is capped at 4095.
Changing it like this makes it match how sysfs_write_file() is
implemented.
This is a static analysis patch. I haven't found any store_attribute()
functions where this change makes a difference.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kees Cook [Fri, 7 Jun 2013 00:07:21 +0000 (10:07 +1000)]
drivers/mtd/chips/gen_probe.c: refactor call to request_module()
This reduces the size of the stack frame when calling request_module().
Performing the sprintf before the call is not needed.
Signed-off-by: Kees Cook <keescook@chromium.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Libo Chen [Fri, 7 Jun 2013 00:07:21 +0000 (10:07 +1000)]
drivers/mfd/lpc_ich.c: convert to module_pci_driver
Signed-off-by: Libo Chen <libo.chen@huawei.com> Cc: Peter Tyser <ptyser@xes-inc.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Cc: Lee Jones <lee.jones@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Zhao Hongjiang [Fri, 7 Jun 2013 00:07:20 +0000 (10:07 +1000)]
drivers/infiniband/core/cm.c: convert to using idr_alloc_cyclic()
commit 3e6628c4b347 ("idr: introduce idr_alloc_cyclic()") adds a new
idr_alloc_cyclic routine and converts several of these users to it. This
is just a missed one - add it.
Signed-off-by: Zhao Hongjiang <zhaohongjiang@huawei.com> Cc: Roland Dreier <roland@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Sean Hefty <sean.hefty@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Bart Van Assche [Fri, 7 Jun 2013 00:07:20 +0000 (10:07 +1000)]
kernel/timer.c: fix jiffies wrap behavior of round_jiffies*()
Make sure that the round_jiffies*() functions return a time that is
in the future when the jiffies counter has recently wrapped.
Signed-off-by: Bart Van Assche <bvanassche@acm.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
posix_timers: fix racy timer delta caching on task exit
When a task exits, we perform a caching of the remaining cputime delta
before expiring of its timers.
This is done from the following places:
* When the task is reaped. We iterate through its list of
posix cpu timers and store the remaining timer delta to
the timer struct instead of the absolute value.
(See posix_cpu_timers_exit() / posix_cpu_timers_exit_group() )
* When we call posix_cpu_timer_get() or posix_cpu_timer_schedule().
If the timer's task is considered dying when watched from these
places, the same conversion from absolute to relative expiry time
is performed. Then the given task's reference is released.
(See clear_dead_task() ).
The relevance of this caching is questionable but this is another
and deeper debate.
The big issue here is that these two sources of caching don't mix
up very well together.
More specifically, the caching can easily be done twice, resulting
in a wrong delta as it gets spuriously substracted a second time by
the elapsed clock. This can happen in the following scenario:
1) The task exits and gets reaped: we call posix_cpu_timers_exit()
and the absolute timer expiry values are converted to a relative
delta.
2) timer_gettime() -> posix_cpu_timer_get() is called and relies on
clear_dead_task() because tsk->exit_state == EXIT_DEAD.
The delta gets substracted again by the elapsed clock and we return
a wrong result.
To fix this, just remove the caching done on task reaping time. It
doesn't bring much value on its own. The caching done from
posix_cpu_timer_get/schedule is enough.
And it would also be hard to get it really right: we could make it put and
clear the target task in the timer struct so that readers know if they are
dealing with a relative cached of absolute value. But it would be racy.
The only safe way to do it would be to lock the itimer->it_lock so that we
know nobody reads the cputime expiry value while we modify it and its
target task reference. Doing so would involve some funny workarounds to
avoid circular lock against the sighand lock. There is just no reason to
maintain this.
The user visible effect of this patch can be observed by running the
following code: it creates a subthread that launches a posix cputimer
which expires after 10 seconds. But then the subthread only busy loops for 2
seconds and exits. The parent reaps the subthread and read the timer value.
Its expected value should the be the initial timer's expiration value
minus the cputime elapsed in the subthread. Roughly 10 - 2 = 8 seconds:
/* Arm 10 sec timer */
err = timer_settime(id, 0, &val, NULL);
if (err < 0) {
perror("Can't set timer\n");
return NULL;
}
/* Exit after 2 seconds of execution */
gettimeofday(&start, NULL);
do {
gettimeofday(&end, NULL);
timersub(&end, &start, &diff);
} while (diff.tv_sec < 2);
return NULL;
}
int main(int argc, char **argv)
{
pthread_t pthread;
int err;
err = pthread_create(&pthread, NULL, thread, NULL);
if (err) {
perror("Can't create thread\n");
return -1;
}
pthread_join(pthread, NULL);
/* Just wait a little bit to make sure the child got reaped */
sleep(1);
err = timer_gettime(id, &new);
if (err)
perror("Can't get timer value\n");
printf("%d %ld\n", new.it_value.tv_sec, new.it_value.tv_nsec);
posix-timers: correctly get dying task time sample in posix_cpu_timer_schedule()
In order to re-arm a timer after it fired, we take a sample of the current
process or thread cputime.
If the task is dying though, we don't arm anything but we cache the
remaining timer expiration delta for further reads.
Something similar is performed in posix_cpu_timer_get() but here we forget
to take the process wide cputime sample before caching it.
As a result we are storing random stack content, leading every further
reads of that timer to return junk values.
Fix this by taking the appropriate sample in the case of process wide
timers.
This probably doesn't matter much in practice because, at this stage, the
thread is the last one in the group and we reached exit_notify(). This
implies that we called exit_itimers() and there should be no more timers
to handle for that task.
So this is likely dead code anyway but let's fix the current logic
and the warning that came along:
kernel/posix-cpu-timers.c: In function 'posix_cpu_timer_schedule':
kernel/posix-cpu-timers.c:1127: warning: 'now' may be used uninitialized in this function
Then we can start to think further about cleaning up that code.
Reported-by: Andrew Morton <akpm@linux-foundation.org> Reported-by: Chen Gang <gang.chen@asianux.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Chen Gang <gang.chen@asianux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add some initial basic tests on a few posix timers interface such as
setitimer() and timer_settime().
These simply check that expiration happens in a reasonable timeframe after
expected elapsed clock time (user time, user + system time, real time,
...).
This is helpful for finding basic breakages while hacking
on this subsystem.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The posix cpu timer expiry time is stored in a union of two types: a 64
bits field if we rely on scheduler precise accounting, or a cputime_t if
we rely on jiffies.
This results in quite some duplicate code and special cases to handle the
two types.
Just unify this into a single 64 bits field. cputime_t can always fit
into it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
remove now-unneeded initialization of ctx_drvdata, remove unneeded braces
Cc: David Brown <davidb@codeaurora.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: James Hogan <james.hogan@imgtec.com> Cc: Libo Chen <clbchenlibo.chen@huawei.com> Cc: Libo Chen <libo.chen@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Libo Chen [Fri, 7 Jun 2013 00:07:17 +0000 (10:07 +1000)]
drivers/iommu/msm_iommu_dev.c: fix leak and clean up error paths
Fix two obvious problems:
1. We have registered msm_iommu_driver first, and need unregister it
when registered msm_iommu_ctx_driver fail
2. We don`t need to kfree drvdata before kzalloc successful.
Signed-off-by: Libo Chen <libo.chen@huawei.com> Acked-by: David Brown <davidb@codeaurora.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: James Hogan <james.hogan@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Ondrej Zary [Fri, 7 Jun 2013 00:07:17 +0000 (10:07 +1000)]
cyber2000fb: avoid palette corruption at higher clocks
When 1280x1024@75Hz mode is set, console palette is not set properly -
sometimes the background is white, sometimes yellow and text colors are
also messed up. This does not happen at 1280x1024@60Hz and below.
It seems that the HW needs some time before setting the palette - maybe
the PLL needs more time to lock at higher speeds. This patch fixes the
problem but without knowing what register to check for PLL lock(?), the
delay might be excessive.
On Fri, 28 Jan 2011 18:15:37 +0000
Russell King <rmk@arm.linux.org.uk> wrote:
> On Tue, Jan 18, 2011 at 01:14:24PM -0800, Andrew Morton wrote:
> > Russell, I have an (old) note here that this is awaiting an ack from
> > yourself?
>
> Well, I can reproduce this problem on the Netwinders here. I'm not sure
> that we should delay all mode switches by one second - and any attempt
> to reduce this value does result in the palette not being set correctly.
>
> For 1280x1024-75, the dotclock is 135MHz, which gives a PLL values of
> 0x41 and 0x06. That's: M=0x41+1, N=0x06+1, P=0x00 (top 2 bits of 0x06)
> -> Q=1
>
> Fpll = 14.31818MHz * M / N
> Fout = Fpll / Q
>
> The PLL itself is formed by dividing the 14-ish MHz frequency by N and
> phase comparing the output of the VCO, divided by M, and adjusting the
> VCO until the two correlate. As VCOs typically tend to have a limited
> range, it's normal to divide the output frequency to produce a greater
> range - and in this case that's done by Q.
>
> For the 800x600-100 copied from /etc/fb.modes, this has a dotclock of
> 67.5MHz, which is exactly half this rate. The PLL values for this are:
> M=0x41+1, N=0x06+1, P=0x01, giving PLL values of 0x41 and 0x46.
>
> Booting with 800x600-100 does not suffer the problem. So it's not
> related to PLL lock time. There's something else going on.
>
> Another experiment I tried was forcing the PLL values to produce 108MHz
> instead of 135MHz. 108MHz is the dotclock for 1280x1024-60. This too
> doesn't suffer the problem.
>
> I've also tried chosing other delay values. 100ms is too short and
> produces the problem, but 1s works. 1s for a PLL to lock is a hell of
> a time, especially for a PLL operating in the MHz range.
>
> I've tried setting the PLL to a known good freqency, and then switching
> to 135MHz - the problem persists. It's not like 135MHz is reaching the
> limits - it'll go up to 206MHz.
>
> So, I don't think this has anything to do with PLL locking. I think
> there's something else going on which isn't immediately obvious - maybe
> bandwidth starvation preventing us from writing properly to the palette?
> As it's a horrible VGA, where you write the same register multiple times
> I wouldn't be surprised if some writes were going missing.
>
> I'll see if I can play around with it some more this evening, but I've
> spent an awful long time on just this issue already this afternoon...
>
> I think further investigation needs to happen on this patch before it's
> acceptable. Or maybe we should prevent the cyberpro coming up in
Signed-off-by: Ondrej Zary <linux@rainbow-software.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Paul Bolle [Fri, 7 Jun 2013 00:07:16 +0000 (10:07 +1000)]
drivers/video/acornfb.c: remove dead code
acornfb checks for HAS_VIDC while support for that macro was removed in
v2.6.23 (when the arm26 port was removed). So we can remove a bit of dead
code.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jeff Mahoney [Fri, 7 Jun 2013 00:07:13 +0000 (10:07 +1000)]
drm/nouveau: make vga_switcheroo code depend on VGA_SWITCHEROO
Commit 8116188fdef594 ("nouveau/acpi: hook up to the MXM method for mux
switching.") broke the build on non-x86 architectures due to the new
dependency on MXM and MXM being an x86 platform driver.
It built previously since the vga switcheroo registration routines were
zereod out on !X86. The code was built in but unused.
This patch makes all of the DSM code depend on CONFIG_VGA_SWITCHEROO,
allowing it to build on non-x86 and shrinking the module size as well.
Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Takashi Iwai [Fri, 7 Jun 2013 00:07:13 +0000 (10:07 +1000)]
drm/cirrus: correct register values for 16bpp
When the mode is set with 16bpp on QEMU, the output gets totally broken.
The culprit is the bogus register values set for 16bpp, which was likely
copied from from a wrong place.
Daniel Vetter [Fri, 7 Jun 2013 00:07:13 +0000 (10:07 +1000)]
drm/fb-helper: don't sleep for screen unblank when an oops is in progress
Otherwise the system will burn even brighter and worse, leave the user
wondering what's going on exactly.
Since we already have a panic handler which will (try) to restore the
entire fbdev console mode, we can just bail out. Inspired by a patch from
Konstantin Khlebnikov. The callchain leading to this, cut&pasted from
Konstantin's original patch:
Note that the entire locking in the fb helper around panic/sysrq and kdbg
is ... non-existant. So we have a decent change of blowing up
everything. But since reworking this ties in with funny concepts like the
fbdev notifier chain or the impressive things which happen around
console_lock while oopsing, I'll leave that as an exercise for braver
souls than me.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Dave Airlie <airlied@gmail.com> Reviewed-by: Rob Clark <robdclark@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Chen Gang [Fri, 7 Jun 2013 00:07:12 +0000 (10:07 +1000)]
kernel/auditfilter.c: fix leak in audit_add_rule() error path
If both 'tree' and 'watch' are valid we must call audit_put_tree(), just
like the preceding code within audit_add_rule().
Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Eric Paris <eparis@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kernel/auditfilter.c:426: warning: this decimal constant is unsigned only in ISO C90
Signed-off-by: Raphael S. Carvalho <raphael.scarv@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Both of these look wrong to me. As Steve Grubb pointed out:
"What we need is 1 PATH record that identifies the MQ. The other PATH
records probably should not be there."
Fix it to record the mq root as a parent, and flag it such that it should
be hidden from view when the names are logged, since the root of the mq
filesystem isn't terribly interesting. With this change, we get a single
PATH record that looks more like this:
In order to do this, a new audit_inode_parent_hidden() function is added.
If we do it this way, then we avoid having the existing callers of
audit_inode needing to do any sort of flag conversion if auditing is
inactive.
Signed-off-by: Jeff Layton <jlayton@redhat.com> Reported-by: Jiri Jaburek <jjaburek@redhat.com> Cc: Steve Grubb <sgrubb@redhat.com> Cc: Eric Paris <eparis@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Wen Congyang [Fri, 7 Jun 2013 00:07:11 +0000 (10:07 +1000)]
x86: make 'mem=' option to work for efi platform
Current mem boot option only can work for non efi environment. If the
user specifies add_efi_memmap, it cannot work for efi environment. In the
efi environment, we call e820_add_region() to add the memory map. So we
can modify __e820_add_region() and the mem boot option can work for efi
environment.
Note: Only E820_RAM is limited, and BOOT_SERVICES_{CODE,DATA} are always
mapped(If its address >= mem_limit, the memory won't be freed in
efi_free_boot_services()).
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Cc: Matt Fleming <matt.fleming@intel.com> Cc: Rob Landley <rob@landley.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yasuaki ISIMATU <isimatu.yasuaki@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Matthew Garrett <mjg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The lockless reclaim hierarchy iterator currently has a misplaced barrier
that can lead to use-after-free crashes.
The reclaim hierarchy iterator consist of a sequence count and a position
pointer that are read and written locklessly, with memory barriers
enforcing ordering.
The write side sets the position pointer first, then updates the sequence
count to "publish" the new position. Likewise, the read side must read
the sequence count first, then the position. If the sequence count is up
to date, it's guaranteed that the position is up to date as well:
writer: reader:
iter->position = position if iter->sequence == expected:
smp_wmb() smp_rmb()
iter->sequence = sequence position = iter->position
However, the read side barrier is currently misplaced, which can lead to
dereferencing stale position pointers that no longer point to valid
memory. Fix this.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Glauber Costa <glommer@parallels.com> Cc: <stable@kernel.org> [3.10+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Akinobu Mita [Fri, 7 Jun 2013 00:07:09 +0000 (10:07 +1000)]
frontswap: fix incorrect zeroing and allocation size for frontswap_map
The bitmap accessed by bitops must have enough size to hold the required
numbers of bits rounded up to a multiple of BITS_PER_LONG. And the bitmap
must not be zeroed by memset() if the number of bits cleared is not a
multiple of BITS_PER_LONG.
This fixes incorrect zeroing and allocation size for frontswap_map. The
incorrect zeroing part doesn't cause any problem because frontswap_map is
freed just after zeroing. But the wrongly calculated allocation size may
cause the problem.
For 32bit systems, the allocation size of frontswap_map is about twice as
large as required size. For 64bit systems, the allocation size is smaller
than requeired if the number of bits is not a multiple of BITS_PER_LONG.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Chen Gang [Fri, 7 Jun 2013 00:07:09 +0000 (10:07 +1000)]
kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules()
audit_add_tree_rule() must set 'rule->tree = NULL;' firstly, to protect
the rule itself freed in kill_rules().
The reason is when it is killed, the 'rule' itself may have already
released, we should not access it. one example: we add a rule to an
inode, just at the same time the other task is deleting this inode.
The work flow for adding a rule:
audit_receive() -> (need audit_cmd_mutex lock)
audit_receive_skb() ->
audit_receive_msg() ->
audit_receive_filter() ->
audit_add_rule() ->
audit_add_tree_rule() -> (need audit_filter_mutex lock)
...
unlock audit_filter_mutex
get_tree()
...
iterate_mounts() -> (iterate all related inodes)
tag_mount() ->
tag_trunk() ->
create_trunk() -> (assume it is 1st rule)
fsnotify_add_mark() ->
fsnotify_add_inode_mark() -> (add mark to inode->i_fsnotify_marks)
...
get_tree(); (each inode will get one)
...
lock audit_filter_mutex
The work flow for deleting an inode:
__destroy_inode() ->
fsnotify_inode_delete() ->
__fsnotify_inode_delete() ->
fsnotify_clear_marks_by_inode() -> (get mark from inode->i_fsnotify_marks)
fsnotify_destroy_mark() ->
fsnotify_destroy_mark_locked() ->
audit_tree_freeing_mark() ->
evict_chunk() ->
...
tree->goner = 1
...
kill_rules() -> (assume current->audit_context == NULL)
call_rcu() -> (rule->tree != NULL)
audit_free_rule_rcu() ->
audit_free_rule()
...
audit_schedule_prune() -> (assume current->audit_context == NULL)
kthread_run() -> (need audit_cmd_mutex and audit_filter_mutex lock)
prune_one() -> (delete it from prue_list)
put_tree(); (match the original get_tree above)
Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: Eric Paris <eparis@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Youquan Song [Fri, 7 Jun 2013 00:07:08 +0000 (10:07 +1000)]
drivers/base/cpu.c: fix maxcpus boot option
The maxcpus boot option limits the maximum number of CPUs in the system,
but this option is broken in recent kernels. Though we use maxcpus to
limit CPUs number, the current kernel will register all of the present
CPUs in sysfs. udev will enumerate all registered cpu in sysfs, and it
will bring up the CPU if the CPU is offline. So the maxcpus option is
broken.
This patch will only register a CPU which is not over the limit of the
maxcpus option in sysfs. So it will keep the maxcpus limitation during
udev enumeration or other bringup of CPUs over the limitation by methods
such as echo 1 > /sys/devices/system/cpu/online
Signed-off-by: Youquan Song <youquan.song@intel.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Naoya Horiguchi [Fri, 7 Jun 2013 00:07:08 +0000 (10:07 +1000)]
mm: migration: add migrate_entry_wait_huge()
When we have a page fault for the address which is backed by a hugepage
under migration, the kernel can't wait correctly and do busy looping on
hugepage fault until the migration finishes. As a result, users who try
to kick hugepage migration (via soft offlining, for example) occasionally
experience long delay or soft lockup.
This is because pte_offset_map_lock() can't get a correct migration entry
or a correct page table lock for hugepage. This patch introduces
migration_entry_wait_huge() to solve this.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <stable@vger.kernel.org> [2.6.35+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/page_alloc.c: fix watermark check in __zone_watermark_ok()
The watermark check consists of two sub-checks. The first one is:
if (free_pages <= min + lowmem_reserve)
return false;
The check assures that there is minimal amount of RAM in the zone. If CMA
is used then the free_pages is reduced by the number of free pages in CMA
prior to the over-mentioned check.
if (!(alloc_flags & ALLOC_CMA))
free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
This prevents the zone from being drained from pages available for
non-movable allocations.
The second check prevents the zone from getting too fragmented.
for (o = 0; o < order; o++) {
free_pages -= z->free_area[o].nr_free << o;
min >>= 1;
if (free_pages <= min)
return false;
}
The field z->free_area[o].nr_free is equal to the number of free pages
including free CMA pages. Therefore the CMA pages are subtracted twice.
This may cause a false positive fail of __zone_watermark_ok() if the CMA
area gets strongly fragmented. In such a case there are many 0-order free
pages located in CMA. Those pages are subtracted twice therefore they
will quickly drain free_pages during the check against fragmentation. The
test fails even though there are many free non-cma pages in the zone.
This patch fixes this issue by subtracting CMA pages only for a purpose of
(free_pages <= min + lowmem_reserve) check.
Laura said:
We were observing allocation failures of higher order pages (order 5 =
128K typically) under tight memory conditions resulting in driver
failure. The output from the page allocation failure showed plenty of
free pages of the appropriate order/type/zone and mostly CMA pages in
the lower orders.
For full disclosure, we still observed some page allocation failures
even after applying the patch but the number was drastically reduced and
those failures were attributed to fragmentation/other system issues.
Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Tested-by: Laura Abbott <lauraa@codeaurora.org> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mel@csn.ul.ie> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Cc: <stable@vger.kernel.org> [3.7+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>