Jingoo Han [Wed, 26 Sep 2012 01:34:20 +0000 (11:34 +1000)]
drivers/video/backlight/kb3886_bl.c: use usleep_range() instead of msleep() for small sleeps
Since msleep() might not sleep for the desired amount when less than 20ms,
use usleep_range().
Signed-off-by: Jingoo Han <jg1.han@samsung.com> Cc: Claudio Nieder <private@claudio.ch> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Sachin Kamat <sachin.kamat@linaro.org> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jingoo Han [Wed, 26 Sep 2012 01:34:20 +0000 (11:34 +1000)]
drivers/video/backlight/ltv350qv.c: use usleep_range() instead of msleep() for small sleeps
Since msleep() might not sleep for the desired amount when less than 20ms,
use usleep_range().
Signed-off-by: Jingoo Han <jg1.han@samsung.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Sachin Kamat <sachin.kamat@linaro.org> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jingoo Han [Wed, 26 Sep 2012 01:34:19 +0000 (11:34 +1000)]
drivers/video/backlight/da9052_bl.c: use usleep_range() instead of msleep() for small sleeps
Since msleep() might not sleep for the desired amount when less than 20ms,
use usleep_range().
Signed-off-by: Jingoo Han <jg1.han@samsung.com> Cc: Ashish Jangam <ashish.jangam@kpitcummins.com> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Sachin Kamat <sachin.kamat@linaro.org> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Joe Perches [Wed, 26 Sep 2012 01:34:19 +0000 (11:34 +1000)]
MAINTAINERS: Update gianfar_ptp after renaming
commit ec21e2ec36769 ("freescale: Move the Freescale drivers")
moved the files, update the pattern.
Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Richard Cochran <richardcochran@gmail.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andy Shevchenko [Wed, 26 Sep 2012 01:34:18 +0000 (11:34 +1000)]
lib/vsprintf: update documentation to cover all of %p[Mm][FR]
Acked-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
George Spelvin [Wed, 26 Sep 2012 01:34:17 +0000 (11:34 +1000)]
lib-vsprintf-optimize-put_dec_trunc8-fix
Rabin Vincent <rabin@rab.in> wrote:
> This patch breaks IP address printing with "%pI4" (and by extension,
> nfsroot). Example:
>
> - Before: 10.0.0.1
> - After: 10...1
Mea culpa, and thank you for catching it! As I said in my earlier
comment, I tested this most extensively wrapped by some sprintf code
that liked 0 converted to a 0-length string, as that works naturally
with the ANSI spec for %.0u. And it turns out not to matter for the
usual printf code, as num_to_str special-cases that anyway.
The fix is straightforward:
Signed-off-by: George Spelvin <linux@horizon.com> Cc: Rabin Vincent <rabin@rab.in> Cc: Denys Vlasenko <vda.linux@googlemail.com> Cc: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
drivers/misc/lis3lv02d: fix some comments specific to lis331dlh driver
Fix some minor problems in comments of lis331dlh driver
* correct comments with respect to 2G sensitivity
* correct typo lis3331dlh mistake to lis331dlh
* add comment to say only 2G range is supported
* change the function name from lis3lv02d_read_16 to
lis331dlh_read_data.
* update i2c_device_id table entry to maintaine consistancy
* update sensor display message
This patch is created based on Eric Piel's review comments on "lis3lv02d:
Add STMicroelectronics lis331dlh digital accelerometer" v2 patch.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com> Cc: Éric Piel <eric.piel@tremplin-utc.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
drivers/misc/lis3lv02d/lis3lv02d_i2c.c: In function 'lis3lv02d_i2c_probe':
drivers/misc/lis3lv02d/lis3lv02d_i2c.c:120: error: implicit declaration of function 'of_match_device'
drivers/misc/lis3lv02d/lis3lv02d_i2c.c:121: error: 'struct lis3lv02d' has no member named 'of_node'
Cc: AnilKumar Ch <anilkumar@ti.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Eric Piel <eric.piel@tremplin-utc.net> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
drivers/misc/lis3lv02d/lis3lv02d_i2c.c: add lis3lv02d device tree init
Add lis3lv02d device tree initialization code/API to take pdata from
device node. Also adds device tree init matching table support to
lis3lv02d_i2c driver. If the driver data is passed from device tree, then
this driver picks up platform data from device node through common/generic
lis3lv02d.c driver.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com> Cc: Eric Piel <eric.piel@tremplin-utc.net> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
drivers/misc/lis3lv02d/lis3lv02d_spi.c: In function 'lis302dl_spi_probe':
drivers/misc/lis3lv02d/lis3lv02d_spi.c:89: error: implicit declaration of function 'of_match_device'
drivers/misc/lis3lv02d/lis3lv02d_spi.c:89: error: 'lis302dl_spi_dt_ids' undeclared (first use in this function)
drivers/misc/lis3lv02d/lis3lv02d_spi.c:89: error: (Each undeclared identifier is reported only once
drivers/misc/lis3lv02d/lis3lv02d_spi.c:89: error: for each function it appears in.)
drivers/misc/lis3lv02d/lis3lv02d_spi.c:90: error: 'struct lis3lv02d' has no member named 'of_node'
Cc: AnilKumar Ch <anilkumar@ti.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Eric Piel <eric.piel@tremplin-utc.net> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
drivers/misc/lis3lv02d/lis3lv02d_spi.c: add lis3lv02d device tree init
Add lis3lv02d device tree initialization code/API to take pdata from
device node. Also remove CONFIG_OF ifdef from the driver, if CONFIG_OF is
not defined then OF APIs returns 0.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com> Cc: Eric Piel <eric.piel@tremplin-utc.net> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Remove lis3lv02d driver device tree initialization from core driver and
move it to individual drivers. With the current implementation some pdata
parameters are missing if we use lis3lv02d_init_device() in lis3lv02d_i2c
driver.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com> Cc: Eric Piel <eric.piel@tremplin-utc.net> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Daniel Mack [Wed, 26 Sep 2012 01:34:14 +0000 (11:34 +1000)]
lis3: lis3lv02d_spi.c: include linux/of.h
This include is needed to define of_match:ptr() for !CONFIG_OF &&
1CONFIG_DTC.
Signed-off-by: Daniel Mack <zonque@gmail.com> Reported-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Daniel Mack [Wed, 26 Sep 2012 01:34:13 +0000 (11:34 +1000)]
misc: lis3: fix undefined reference to lis3lv02d_init_dt
Export the symbol to fix linker errors.
Signed-off-by: Daniel Mack <zonque@gmail.com> Reported-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
orderly_poweroff is trying to poweroff platform in two steps:
step 1: Call user space application to poweroff
step 2: If user space poweroff fail, then do a force power off if force param
is set.
The bug here is, step 1 is always successful with param UMH_NO_WAIT, which obey
the design goal of orderly_poweroff.
We have two choices here:
UMH_WAIT_EXEC which means wait for the exec, but not the process;
UMH_WAIT_PROC which means wait for the process to complete.
we need to trade off the two choices:
If using UMH_WAIT_EXEC, there is potential issue comments by Serge E.
Hallyn: The exec will have started, but may for whatever (very unlikely)
reason fail.
If using UMH_WAIT_PROC, there is potential issue comments by Eric W.
Biederman: If the caller is not running in a kernel thread then we can
easily get into a case where the user space caller will block waiting for
us when we are waiting for the user space caller.
Thanks for their excellent ideas, based on the above discussion, we
finally choose UMH_WAIT_EXEC, which is much more safe, if the user
application really fails, we just complain the application itself, it
seems a better choice here.
Signed-off-by: Feng Hong <hongfeng@marvell.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()
As kernel_power_off() calls disable_nonboot_cpus(), we may also want to
have kernel_restart() call disable_nonboot_cpus(). Doing so can help
machines that require boot cpu be the last alive cpu during reboot to
survive with kernel restart.
This fixes one reboot issue seen on imx6q (Cortex-A9 Quad). The machine
requires that the restart routine be run on the primary cpu rather than
secondary ones. Otherwise, the secondary core running the restart routine
will fail to come to online after reboot.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Historically, the top three bytes of personality have been used for things
such as ADDR_NO_RANDOMIZE, which made sense only for specific
architectures.
We now however have a flag there that is general no matter the
architecture (UNAME26); generally we have to be careful to preserve the
personality flags across exec().
This patch fixes tile architecture not to forcefully overwrite personality
flags during exec().
In addition to that, we fix two other things along the way:
- exec_domain switching is fixed -- set_personality() should always
be used instead of directly assigning to current->personality.
- as pointed out by Arnd Bergmann, PER_LINUX_32BIT is not used anywhere
by tile, so let's just drop that in favor of PER_LINUX
Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
cross-arch: don't corrupt personality flags upon exec()
Historically, the top three bytes of personality have been used for things
such as ADDR_NO_RANDOMIZE, which made sense only for specific
architectures.
We now however have a flag there that is general no matter the
architecture (UNAME26); generally we have to be careful to preserve the
personality flags across exec().
This patch tries to fix all architectures that forcefully overwrite
personality flags during exec() (ppc32 and s390 have been fixed recently
by commits f9783ec86 and 59e4c3a2f in a similar way already).
Signed-off-by: Jiri Kosina <jkosina@suse.cz> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Mark Salter <msalter@redhat.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Chen Liqin <liqin.chen@sunplusct.com> Cc: Lennox Wu <lennox.wu@gmail.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Zankel <chris@zankel.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit 6afe1a1fe8ff83f6a ("PM: Remove legacy PM") removed the
initialization of retval, causing:
arch/frv/kernel/pm.c: In function 'sysctl_pm_do_suspend':
arch/frv/kernel/pm.c:165:5: warning: 'retval' may be used uninitialized in this function [-Wuninitialized]
Remove the variable completely to fix this, and convert to a proper
switch (...) { ... } construct to improve readability.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Joe Mario [Wed, 26 Sep 2012 01:34:11 +0000 (11:34 +1000)]
sections: fix const sections for crc32 table
Fix the const sections for the code generated by crc32 table. There's no
ro version of the cacheline aligned section, so we cannot put in const
data without a conflict Just don't make the crc tables const for now.
[ak@linux.intel.com: some fixes and new description] Signed-off-by: Joe Mario <jmario@redhat.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Oliver Hartkopp <socketcan@hartkopp.net> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
sections: fix section conflicts in drivers/net/wan
Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Krzysztof Halasa <khc@pm.waw.pl> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The PA-RISC tool chain seems to have some problem with correct read/write
attributes on sections. This causes problems when the const sections
are fixed up for other architecture to only contain truly read-only
data.
Petr Holasek [Wed, 26 Sep 2012 01:34:01 +0000 (11:34 +1000)]
KSM: numa awareness sysfs knob
Introduces new sysfs boolean knob /sys/kernel/mm/ksm/merge_across_nodes
which control merging pages across different numa nodes. When it is set
to zero only pages from the same node are merged, otherwise pages from all
nodes can be merged together (default behavior).
Typical use-case could be a lot of KVM guests on NUMA machine and cpus
from more distant nodes would have significant increase of access latency
to the merged ksm page. Sysfs knob was choosen for higher variability
when some users still prefers higher amount of saved physical memory
regardless of access latency.
Every numa node has its own stable & unstable trees because of faster
searching and inserting. Changing of merge_nodes value is possible only
when there are not any ksm shared pages in system.
I've tested this patch on numa machines with 2, 4 and 8 nodes and measured
speed of memory access inside of KVM guests with memory pinned to one of
nodes with this benchmark:
http://pholasek.fedorapeople.org/alloc_pg.c
Population standard deviations of access times in percentage of average
were following:
Simply remove UNEVICTABLE_MLOCKFREED and unevictable_pgs_mlockfreed line
from /proc/vmstat: Johannes and Mel point out that it was very unlikely to
have been used by any tool, and of course we can restore it easily enough
if that turns out to be wrong.
Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Minchan Kim [Wed, 26 Sep 2012 01:34:00 +0000 (11:34 +1000)]
memory-hotplug: fix zone stat mismatch
During memory-hotplug, I found NR_ISOLATED_[ANON|FILE] are increasing,
causing the kernel to hang. When the system doesn't have enough free
pages, it enters reclaim but never reclaim any pages due to
too_many_isolated()==true and loops forever.
The cause is that when we do memory-hotadd after memory-remove,
__zone_pcp_update() clears a zone's ZONE_STAT_ITEMS in setup_pageset()
although the vm_stat_diff of all CPUs still have values.
In addtion, when we offline all pages of the zone, we reset them in
zone_pcp_reset without draining so we loss some zone stat item.
Minchan Kim [Wed, 26 Sep 2012 01:34:00 +0000 (11:34 +1000)]
Revert 0def08e3 because check_range can't fail in migrate_to_node with
considering current usecases.
Quote from Johannes
: I think it makes sense to revert. Not because of the semantics, but I
: just don't see how check_range() could even fail for this callsite:
:
: 1. we pass mm->mmap->vm_start in there, so we should not fail due to
: find_vma()
:
: 2. we pass MPOL_MF_DISCONTIG_OK, so the discontig checks do not apply
: and so can not fail
:
: 3. we pass MPOL_MF_MOVE | MPOL_MF_MOVE_ALL, the page table loops will
: continue until addr == end, so we never fail with -EIO
And I added a new VM_BUG_ON for checking migrate_to_node's future usecase
which might pass to MPOL_MF_STRICT.
Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vasiliy Kulikov <segooon@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Haggai Eran [Wed, 26 Sep 2012 01:33:59 +0000 (11:33 +1000)]
mm: call invalidate_range_end in do_wp_page even for zero pages
The previous patch "mm: wrap calls to set_pte_at_notify with
invalidate_range_start and invalidate_range_end" only called the
invalidate_range_end mmu notifier function in do_wp_page when the new_page
variable wasn't NULL. This was done in order to only call
invalidate_range_end after invalidate_range_start was called.
Unfortunately, there are situations where new_page is NULL and
invalidate_range_start is called. This caused invalidate_range_start to
be called without a matching invalidate_range_end, causing kvm to loop
indefinitely on the first page fault.
This patch adds a flag variable to do_wp_page that marks whether the
invalidate_range_start notifier was called. invalidate_range_end is then
called if the flag is true.
Reported-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Haggai Eran <haggaie@mellanox.com> Cc: Andrea Arcangeli <andrea@qumranet.com> Cc: Sagi Grimberg <sagig@mellanox.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Or Gerlitz <ogerlitz@mellanox.com> Cc: Haggai Eran <haggaie@mellanox.com> Cc: Shachar Raindel <raindel@mellanox.com> Cc: Liran Liss <liranl@mellanox.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Haggai Eran [Wed, 26 Sep 2012 01:33:59 +0000 (11:33 +1000)]
mm: wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end
In order to allow sleeping during invalidate_page mmu notifier calls, we
need to avoid calling when holding the PT lock. In addition to its direct
calls, invalidate_page can also be called as a substitute for a change_pte
call, in case the notifier client hasn't implemented change_pte.
This patch drops the invalidate_page call from change_pte, and instead
wraps all calls to change_pte with invalidate_range_start and
invalidate_range_end calls.
Note that change_pte still cannot sleep after this patch, and that clients
implementing change_pte should not take action on it in case the number of
outstanding invalidate_range_start calls is larger than one, otherwise
they might miss a later invalidation.
Signed-off-by: Haggai Eran <haggaie@mellanox.com> Cc: Andrea Arcangeli <andrea@qumranet.com> Cc: Sagi Grimberg <sagig@mellanox.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Or Gerlitz <ogerlitz@mellanox.com> Cc: Haggai Eran <haggaie@mellanox.com> Cc: Shachar Raindel <raindel@mellanox.com> Cc: Liran Liss <liranl@mellanox.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: move all mmu notifier invocations to be done outside the PT lock
In order to allow sleeping during mmu notifier calls, we need to avoid
invoking them under the page table spinlock. This patch solves the
problem by calling invalidate_page notification after releasing the lock
(but before freeing the page itself), or by wrapping the page invalidation
with calls to invalidate_range_begin and invalidate_range_end.
To prevent accidental changes to the invalidate_range_end arguments after
the call to invalidate_range_begin, the patch introduces a convention of
saving the arguments in consistently named locals:
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
The patch changes code to use this convention for all calls to
mmu_notifier_invalidate_range_start/end, except those where the calls are
close enough so that anyone who glances at the code can see the values
aren't changing.
This patchset is a preliminary step towards on-demand paging design to be
added to the RDMA stack.
Why do we want on-demand paging for Infiniband?
Applications register memory with an RDMA adapter using system calls,
and subsequently post IO operations that refer to the corresponding
virtual addresses directly to HW. Until now, this was achieved by
pinning the memory during the registration calls. The goal of on demand
paging is to avoid pinning the pages of registered memory regions (MRs).
This will allow users the same flexibility they get when swapping any
other part of their processes address spaces. Instead of requiring the
entire MR to fit in physical memory, we can allow the MR to be larger,
and only fit the current working set in physical memory.
Why should anyone care? What problems are users currently experiencing?
This can make programming with RDMA much simpler. Today, developers
that are working with more data than their RAM can hold need either to
deregister and reregister memory regions throughout their process's
life, or keep a single memory region and copy the data to it. On demand
paging will allow these developers to register a single MR at the
beginning of their process's life, and let the operating system manage
which pages needs to be fetched at a given time. In the future, we
might be able to provide a single memory access key for each process
that would provide the entire process's address as one large memory
region, and the developers wouldn't need to register memory regions at
all.
Is there any prospect that any other subsystems will utilise these
infrastructural changes? If so, which and how, etc?
As for other subsystems, I understand that XPMEM wanted to sleep in
MMU notifiers, as Christoph Lameter wrote at
http://lkml.indiana.edu/hypermail/linux/kernel/0802.1/0460.html and
perhaps Andrea knows about other use cases.
Scheduling in mmu notifications is required since we need to sync the
hardware with the secondary page tables change. A TLB flush of an IO
device is inherently slower than a CPU TLB flush, so our design works by
sending the invalidation request to the device, and waiting for an
interrupt before exiting the mmu notifier handler.
Avi said:
kvm may be a buyer. kvm::mmu_lock, which serializes guest page
faults, also protects long operations such as destroying large ranges.
It would be good to convert it into a spinlock, but as it is used inside
mmu notifiers, this cannot be done.
(there are alternatives, such as keeping the spinlock and using a
generation counter to do the teardown in O(1), which is what the "may"
is doing up there).
[akpm@linux-foundation.orgpossible speed tweak in hugetlb_cow(), cleanups] Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Haggai Eran <haggaie@mellanox.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Or Gerlitz <ogerlitz@mellanox.com> Cc: Haggai Eran <haggaie@mellanox.com> Cc: Shachar Raindel <raindel@mellanox.com> Cc: Liran Liss <liranl@mellanox.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Wed, 26 Sep 2012 01:33:58 +0000 (11:33 +1000)]
hugetlb: do not use vma_hugecache_offset() for vma_prio_tree_foreach
0c176d5 ("mm: hugetlb: fix pgoff computation when unmapping page from
vma") fixed pgoff calculation but it has replaced it by
vma_hugecache_offset() which is not approapriate for offsets used for
vma_prio_tree_foreach() because that one expects index in page units
rather than in huge_page_shift.
Using vma_hugecache_offset() is not incorrect because the pgoff will fit
into the same vmas but it is confusing so the standard PAGE_SHIFT based
index calculation is used instead.
Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Hillf Danton <dhillf@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrea Arcangeli [Wed, 26 Sep 2012 01:33:58 +0000 (11:33 +1000)]
mm: thp: fix pmd_present for split_huge_page and PROT_NONE with THP
In many places !pmd_present has been converted to pmd_none. For pmds
that's equivalent and pmd_none is quicker so using pmd_none is better.
However (unless we delete pmd_present) we should provide an accurate
pmd_present too. This will avoid the risk of code thinking the pmd is non
present because it's under __split_huge_page_map, see the pmd_mknotpresent
there and the comment above it.
If the page has been mprotected as PROT_NONE, it would also lead to a
pmd_present false negative in the same way as the race with
split_huge_page.
Because the PSE bit stays on at all times (both during split_huge_page and
when the _PAGE_PROTNONE bit get set), we could only check for the PSE bit,
but checking the PROTNONE bit too is still good to remember pmd_present
must always keep PROT_NONE into account.
This explains a not reproducible BUG_ON that was seldom reported on the
lists.
The same issue is in pmd_large, it would go wrong with both PROT_NONE and
if it races with split_huge_page.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andi removed some outedated documentation from Documentation/memory.txt
back in 2009 by 3b2b9a875dd ("Documentation/memory.txt: remove some very
outdated recommendations"), but the resulting document is not in a nice
shape either.
It seems to me like we are not losing anything by completely removing the
file now.
Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Rientjes [Wed, 26 Sep 2012 01:33:57 +0000 (11:33 +1000)]
mm, numa: reclaim from all nodes within reclaim distance
RECLAIM_DISTANCE represents the distance between nodes at which it is
deemed too costly to allocate from; it's preferred to try to reclaim from
a local zone before falling back to allocating on a remote node with such
a distance.
To do this, zone_reclaim_mode is set if the distance between any two
nodes on the system is greather than this distance. This, however, ends
up causing the page allocator to reclaim from every zone regardless of
its affinity.
What we really want is to reclaim only from zones that are closer than
RECLAIM_DISTANCE. This patch adds a nodemask to each node that
represents the set of nodes that are within this distance. During the
zone iteration, if the bit for a zone's node is set for the local node,
then reclaim is attempted; otherwise, the zone is skipped.
Signed-off-by: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We should not be seeing non-0 unevictable_pgs_mlockfreed any longer. So
remove free_page_mlock() from the page freeing paths: __PG_MLOCKED is
already in PAGE_FLAGS_CHECK_AT_FREE, so free_pages_check() will now be
checking it, reporting "BUG: Bad page state" if it's ever found set.
Comment UNEVICTABLE_MLOCKFREED and unevictable_pgs_mlockfreed always 0.
Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We had thought that pages could no longer get freed while still marked as
mlocked; but Johannes Weiner posted this program to demonstrate that
truncating an mlocked private file mapping containing COWed pages is still
mishandled:
The anon COWed pages are not caught by truncation's clear_page_mlock() of
the pagecache pages; but unmap_mapping_range() unmaps them, so we ought to
look out for them there in page_remove_rmap(). Indeed, why should
truncation or invalidation be doing the clear_page_mlock() when removing
from pagecache? mlock is a property of mapping in userspace, not a
property of pagecache: an mlocked unmapped page is nonsensical.
Reported-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
page_evictable(page, vma) is an irritant: almost all its callers pass
NULL for vma. Remove the vma arg and use mlocked_vma_newpage(vma, page)
explicitly in the couple of places it's needed. But in those places we
don't even need page_evictable() itself! They're dealing with a freshly
allocated anonymous page, which has no "mapping" and cannot be mlocked yet.
Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In fuzzing with trinity, lockdep protested "possible irq lock inversion
dependency detected" when isolate_lru_page() reenabled interrupts while
still holding the supposedly irq-safe tree_lock:
isolate_lru_page() is correct to enable interrupts unconditionally:
invalidate_complete_page2() is incorrect to call clear_page_mlock() while
holding tree_lock, which is supposed to nest inside lru_lock.
Both truncate_complete_page() and invalidate_complete_page() call
clear_page_mlock() before taking tree_lock to remove page from radix_tree.
I guess invalidate_complete_page2() preferred to test PageDirty (again)
under tree_lock before committing to the munlock; but since the page has
already been unmapped, its state is already somewhat inconsistent, and no
worse if clear_page_mlock() moved up.
Reported-by: Sasha Levin <levinsasha928@gmail.com> Deciphered-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Wed, 26 Sep 2012 01:33:56 +0000 (11:33 +1000)]
memcg: move mem_cgroup_is_root upwards
kmem code uses this function and it is better to not use forward
declarations for static inline functions as some (older) compilers don't
like it:
gcc version 4.3.4 [gcc-4_3-branch revision 152973] (SUSE Linux)
mm/memcontrol.c:421: warning: `mem_cgroup_is_root' declared inline after being called
mm/memcontrol.c:421: warning: previous declaration of `mem_cgroup_is_root' was here
Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@parallels.com> Cc: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Wed, 26 Sep 2012 01:33:55 +0000 (11:33 +1000)]
memcg: cleanup kmem tcp ifdefs
TCP kmem accounting is currently guarded by CONFIG_MEMCG_KMEM ifdefs but
the code is not used if !CONFIG_INET so we should rather test for both.
The same applies to net/sock.h, net/ip.h and net/tcp_memcontrol.h but
let's keep those outside of any ifdefs because it is considered safer wrt.
future maintainability.
Michael Kerrisk [Wed, 26 Sep 2012 01:33:55 +0000 (11:33 +1000)]
memcg: trivial fixes for Documentation/cgroups/memory.txt
While reading through Documentation/cgroups/memory.txt, I found a number
of minor wordos and typos. The patch below is a conservative handling of
some of these: it provides just a number of "obviously correct" fixes to
the English that improve the readability of the document somewhat.
Obviously some more significant fixes need to be made to the document, but
some of those may not be in the "obvious correct" category.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
but is now:
zone->present_pages = spanned pages - absent pages - memmap pages.
spanned pages: total size, including holes.
absent pages: holes.
bootmem pages: pages used in system boot, managed by bootmem allocator.
memmap pages: pages used by page structs.
This may cause zone->present_pages less than it should be. For example,
numa node 1 has ZONE_NORMAL and ZONE_MOVABLE, it's memmap and other
bootmem will be allocated from ZONE_MOVABLE, so ZONE_NORMAL's
present_pages should be spanned pages - absent pages, but now it also
minus memmap pages(free_area_init_core), which are actually allocated from
ZONE_MOVABLE. When offlining all memory of a zone, this will cause
zone->present_pages less than 0, because present_pages is unsigned long
type, it is actually a very large integer, it indirectly caused
zone->watermark[WMARK_MIN] becomes a large
integer(setup_per_zone_wmarks()), than cause totalreserve_pages become a
large integer(calculate_totalreserve_pages()), and finally cause memory
allocating failure when fork process(__vm_enough_memory()).
Now that lumpy reclaim has been removed, compaction is the only way left
to free up contiguous memory areas. It is time to just enable
CONFIG_COMPACTION by default.
Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Acked-by: Rafael Aquini <aquini@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: thp: fix the update_mmu_cache() last argument passing in mm/huge_memory.c
The update_mmu_cache() takes a pointer (to pte_t by default) as the last
argument but the huge_memory.c passes a pmd_t value. The patch changes
the argument to the pmd_t * pointer.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Michal Hocko <mhocko@suse.cz> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Minchan Kim [Wed, 26 Sep 2012 01:33:53 +0000 (11:33 +1000)]
memory-hotplug: don't replace lowmem pages with highmem
The changelog for 6a6dccba2 ("mm: cma: don't replace lowmem pages with
highmem") mentioned that lowmem pages can be replaced by highmem pages
during CMA migration. 6a6dccba2 fixed that issue.
Quote from that changelog:
: The filesystem layer expects pages in the block device's mapping to not
: be in highmem (the mapping's gfp mask is set in bdget()), but CMA can
: currently replace lowmem pages with highmem pages, leading to crashes in
: filesystem code such as the one below:
:
: Unable to handle kernel NULL pointer dereference at virtual address 00000400
: pgd = c0c98000
: [00000400] *pgd=00c91831, *pte=00000000, *ppte=00000000
: Internal error: Oops: 817 [#1] PREEMPT SMP ARM
: CPU: 0 Not tainted (3.5.0-rc5+ #80)
: PC is at __memzero+0x24/0x80
: ...
: Process fsstress (pid: 323, stack limit = 0xc0cbc2f0)
: Backtrace:
: [<c010e3f0>] (ext4_getblk+0x0/0x180) from [<c010e58c>] (ext4_bread+0x1c/0x98)
: [<c010e570>] (ext4_bread+0x0/0x98) from [<c0117944>] (ext4_mkdir+0x160/0x3bc)
: r4:c15337f0
: [<c01177e4>] (ext4_mkdir+0x0/0x3bc) from [<c00c29e0>] (vfs_mkdir+0x8c/0x98)
: [<c00c2954>] (vfs_mkdir+0x0/0x98) from [<c00c2a60>] (sys_mkdirat+0x74/0xac)
: r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0
: [<c00c29ec>] (sys_mkdirat+0x0/0xac) from [<c00c2ab8>] (sys_mkdir+0x20/0x24)
: r6:beccdcf0 r5:00074000 r4:beccdbbc
: [<c00c2a98>] (sys_mkdir+0x0/0x24) from [<c000e3c0>] (ret_fast_syscall+0x0/0x30)
Memory-hotplug has same problem as CMA has so the same fix can be applied
to memory-hotplug as well.
Fix it by reusing.
Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: Restart compaction from near where it left off
This is almost entirely based on Rik's previous patches and discussions
with him about how this might be implemented.
Order > 0 compaction stops when enough free pages of the correct page
order have been coalesced. When doing subsequent higher order
allocations, it is possible for compaction to be invoked many times.
However, the compaction code always starts out looking for things to
compact at the start of the zone, and for free pages to compact things to
at the end of the zone.
This can cause quadratic behaviour, with isolate_freepages starting at the
end of the zone each time, even though previous invocations of the
compaction code already filled up all free memory on that end of the zone.
This can cause isolate_freepages to take enormous amounts of CPU with
certain workloads on larger memory systems.
This patch caches where the migration and free scanner should start from
on subsequent compaction invocations using the pageblock-skip information.
When compaction starts it begins from the cached restart points and will
update the cached restart points until a page is isolated or a pageblock
is skipped that would have been scanned by synchronous compaction.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: cache if a pageblock was scanned and no pages were isolated
When compaction was implemented it was known that scanning could
potentially be excessive. The ideal was that a counter be maintained for
each pageblock but maintaining this information would incur a severe
penalty due to a shared writable cache line. It has reached the point
where the scanning costs are a serious problem, particularly on
long-lived systems where a large process starts and allocates a large
number of THPs at the same time.
Instead of using a shared counter, this patch adds another bit to the
pageblock flags called PG_migrate_skip. If a pageblock is scanned by
either migrate or free scanner and 0 pages were isolated, the pageblock is
marked to be skipped in the future. When scanning, this bit is checked
before any scanning takes place and the block skipped if set.
The main difficulty with a patch like this is "when to ignore the cached
information?" If it's ignored too often, the scanning rates will still be
excessive. If the information is too stale then allocations will fail
that might have otherwise succeeded. In this patch
o CMA always ignores the information
o If the migrate and free scanner meet then the cached information will
be discarded if it's at least 5 seconds since the last time the cache
was discarded
o If there are a large number of allocation failures, discard the cache.
The time-based heuristic is very clumsy but there are few choices for a
better event. Depending solely on multiple allocation failures still
allows excessive scanning when THP allocations are failing in quick
succession due to memory pressure. Waiting until memory pressure is
relieved would cause compaction to continually fail instead of using
reclaim/compaction to try allocate the page. The time-based mechanism is
clumsy but a better option is not obvious.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Revert "mm: have order > 0 compaction start off where it left"
This reverts commit 7db8889a ("mm: have order > 0 compaction start off
where it left") and commit de74f1cc ("mm: have order > 0 compaction start
near a pageblock with free pages"). These patches were a good idea and
tests confirmed that they massively reduced the amount of scanning but the
implementation is complex and tricky to understand. A later patch will
cache what pageblocks should be skipped and reimplements the concept of
compact_cached_free_pfn on top for both migration and free scanners.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: iron out isolate_freepages_block() and isolate_freepages_range()
Andrew pointed out that isolate_freepages_block() is "straggly" and
isolate_freepages_range() is making assumptions on how compact_control is
used which is delicate. This patch straightens isolate_freepages_block()
and makes it fly straight and initialses compact_control to zeros in
isolate_freepages_range(). The code should be easier to follow and is
functionally equivalent. The CMA failure path is now a little more
expensive but that is a marginal corner-case.
Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Cc: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: acquire the zone->lock as late as possible
Compaction's free scanner acquires the zone->lock when checking for
PageBuddy pages and isolating them. It does this even if there are no
PageBuddy pages in the range.
This patch defers acquiring the zone lock for as long as possible. In the
event there are no free pages in the pageblock then the lock will not be
acquired at all which reduces contention on zone->lock.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: acquire the zone->lru_lock as late as possible
Richard Davies and Shaohua Li have both reported lock contention problems
in compaction on the zone and LRU locks as well as significant amounts of
time being spent in compaction. This series aims to reduce lock
contention and scanning rates to reduce that CPU usage. Richard reported
at https://lkml.org/lkml/2012/9/21/91 that this series made a big
different to a problem he reported in August
(http://marc.info/?l=kvm&m=134511507015614&w=2).
Patch 1 defers acquiring the zone->lru_lock as long as possible.
Patch 2 defers acquiring the zone->lock as lock as possible.
Patch 3 reverts Rik's "skip-free" patches as the core concept gets
reimplemented later and the remaining patches are easier to
understand if this is reverted first.
Patch 4 adds a pageblock-skip bit to the pageblock flags to cache what
pageblocks should be skipped by the migrate and free scanners.
This drastically reduces the amount of scanning compaction has
to do.
Patch 5 reimplements something similar to Rik's idea except it uses the
pageblock-skip information to decide where the scanners should
restart from and does not need to wrap around.
I tested this on 3.6-rc6 + linux-next/akpm. Kernels tested were
Stress high-order allocation tests looked ok. Success rates are more or
less the same with the full series applied but there is an expectation
that there is less opportunity to race with other allocation requests if
there is less scanning. The time to complete the tests did not vary that
much and are uninteresting as were the vmstat statistics so I will not
present them here.
Using ftrace I recorded how much scanning was done by compaction and got this
The efficiency is worthless because of the nature of the test and the
number of failures. The really interesting point as far as this patch
series is concerned is the number of pages scanned. Note that reverting
Rik's patches massively increases the number of pages scanned indicating
that those patches really did make a difference to CPU usage.
However, caching what pageblocks should be skipped has a much higher
impact. With patches 1-8 applied, free page and migrate page scanning are
both reduced by 95% in comparison to the akpm kernel. If the basic
concept of Rik's patches are implemened on top then scanning then the free
scanner barely changed but migrate scanning was further reduced. That
said, tests on 3.6-rc5 indicated that the last patch had greater impact
than what was measured here so it is a bit variable.
One way or the other, this series has a large impact on the amount of
scanning compaction does when there is a storm of THP allocations.
This patch:
Compaction's migrate scanner acquires the zone->lru_lock when scanning a
range of pages looking for LRU pages to acquire. It does this even if
there are no LRU pages in the range. If multiple processes are compacting
then this can cause severe locking contention. To make matters worse
commit b2eef8c0 ("mm: compaction: minimise the time IRQs are disabled
while isolating pages for migration") releases the lru_lock every
SWAP_CLUSTER_MAX pages that are scanned.
This patch makes two changes to how the migrate scanner acquires the LRU
lock. First, it only releases the LRU lock every SWAP_CLUSTER_MAX pages
if the lock is contended. This reduces the number of times it
unnecessarily disables and re-enables IRQs. The second is that it defers
acquiring the LRU lock for as long as possible. If there are no LRU pages
or the only LRU pages are transhuge then the LRU lock will not be acquired
at all which reduces contention on zone->lru_lock.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Richard Davies <richard@arachsys.com> Cc: Shaohua Li <shli@kernel.org> Cc: Avi Kivity <avi@redhat.com> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: move fatal signal check out of compact_checklock_irqsave
c67fe3752 ("mm: compaction: Abort async compaction if locks are contended
or taking too long") addressed a lock contention problem in compaction by
introducing compact_checklock_irqsave() that effecively aborting async
compaction in the event of compaction.
To preserve existing behaviour it also moved a fatal_signal_pending()
check into compact_checklock_irqsave() but that is very misleading. It
"hides" the check within a locking function but has nothing to do with
locking as such. It just happens to work in a desirable fashion.
This patch moves the fatal_signal_pending() check to
isolate_migratepages_range() where it belongs. Arguably the same check
should also happen when isolating pages for freeing but it's overkill.
Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Shaohua Li <shli@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
projects / karo-tx-linux.git / log