29 Oct, 2011
1 commit
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* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue: (21 commits)
leases: fix write-open/read-lease race
nfs: drop unnecessary locking in llseek
ext4: replace cut'n'pasted llseek code with generic_file_llseek_size
vfs: add generic_file_llseek_size
vfs: do (nearly) lockless generic_file_llseek
direct-io: merge direct_io_walker into __blockdev_direct_IO
direct-io: inline the complete submission path
direct-io: separate map_bh from dio
direct-io: use a slab cache for struct dio
direct-io: rearrange fields in dio/dio_submit to avoid holes
direct-io: fix a wrong comment
direct-io: separate fields only used in the submission path from struct dio
vfs: fix spinning prevention in prune_icache_sb
vfs: add a comment to inode_permission()
vfs: pass all mask flags check_acl and posix_acl_permission
vfs: add hex format for MAY_* flag values
vfs: indicate that the permission functions take all the MAY_* flags
compat: sync compat_stats with statfs.
vfs: add "device" tag to /proc/self/mountstats
cleanup: vfs: small comment fix for block_invalidatepage
...Fix up trivial conflict in fs/gfs2/file.c (llseek changes)
28 Oct, 2011
1 commit
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Currently, when you call iov_iter_advance, then the pointer to the iovec
array can be incremented, but it does not decrement the nr_segs value in
the iov_iter struct. The result is a iov_iter struct with a nr_segs
value that goes beyond the end of the array.While I'm not aware of anything that's specifically broken by this, it
seems odd and a bit dangerous not to decrement that value. If someone
were to trust the nr_segs value to be correct, then they could end up
walking off the end of the array.Changing this might also provide some micro-optimization when dealing
with the last iovec in an array. Many of the other routines that deal
with iov_iter have optimized codepaths when nr_segs == 1.Cc: Nick Piggin
Signed-off-by: Jeff Layton
Signed-off-by: Christoph Hellwig
26 Oct, 2011
1 commit
25 Oct, 2011
2 commits
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* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (59 commits)
MAINTAINERS: linux-m32r is moderated for non-subscribers
linux@lists.openrisc.net is moderated for non-subscribers
Drop default from "DM365 codec select" choice
parisc: Kconfig: cleanup Kernel page size default
Kconfig: remove redundant CONFIG_ prefix on two symbols
cris: remove arch/cris/arch-v32/lib/nand_init.S
microblaze: add missing CONFIG_ prefixes
h8300: drop puzzling Kconfig dependencies
MAINTAINERS: microblaze-uclinux@itee.uq.edu.au is moderated for non-subscribers
tty: drop superfluous dependency in Kconfig
ARM: mxc: fix Kconfig typo 'i.MX51'
Fix file references in Kconfig files
aic7xxx: fix Kconfig references to READMEs
Fix file references in drivers/ide/
thinkpad_acpi: Fix printk typo 'bluestooth'
bcmring: drop commented out line in Kconfig
btmrvl_sdio: fix typo 'btmrvl_sdio_sd6888'
doc: raw1394: Trivial typo fix
CIFS: Don't free volume_info->UNC until we are entirely done with it.
treewide: Correct spelling of successfully in comments
... -
* 'next' of git://selinuxproject.org/~jmorris/linux-security: (95 commits)
TOMOYO: Fix incomplete read after seek.
Smack: allow to access /smack/access as normal user
TOMOYO: Fix unused kernel config option.
Smack: fix: invalid length set for the result of /smack/access
Smack: compilation fix
Smack: fix for /smack/access output, use string instead of byte
Smack: domain transition protections (v3)
Smack: Provide information for UDS getsockopt(SO_PEERCRED)
Smack: Clean up comments
Smack: Repair processing of fcntl
Smack: Rule list lookup performance
Smack: check permissions from user space (v2)
TOMOYO: Fix quota and garbage collector.
TOMOYO: Remove redundant tasklist_lock.
TOMOYO: Fix domain transition failure warning.
TOMOYO: Remove tomoyo_policy_memory_lock spinlock.
TOMOYO: Simplify garbage collector.
TOMOYO: Fix make namespacecheck warnings.
target: check hex2bin result
encrypted-keys: check hex2bin result
...
20 Oct, 2011
1 commit
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I don't usually pay much attention to the stale "? " addresses in
stack backtraces, but this lucky report from Pawel Sikora hints that
mremap's move_ptes() has inadequate locking against page migration.3.0 BUG_ON(!PageLocked(p)) in migration_entry_to_page():
kernel BUG at include/linux/swapops.h:105!
RIP: 0010:[] []
migration_entry_wait+0x156/0x160
[] handle_pte_fault+0xae1/0xaf0
[] ? __pte_alloc+0x42/0x120
[] ? do_huge_pmd_anonymous_page+0xab/0x310
[] handle_mm_fault+0x181/0x310
[] ? vma_adjust+0x537/0x570
[] do_page_fault+0x11d/0x4e0
[] ? do_mremap+0x2d5/0x570
[] page_fault+0x1f/0x30mremap's down_write of mmap_sem, together with i_mmap_mutex or lock,
and pagetable locks, were good enough before page migration (with its
requirement that every migration entry be found) came in, and enough
while migration always held mmap_sem; but not enough nowadays, when
there's memory hotremove and compaction.The danger is that move_ptes() lets a migration entry dodge around
behind remove_migration_pte()'s back, so it's in the old location when
looking at the new, then in the new location when looking at the old.Either mremap's move_ptes() must additionally take anon_vma lock(), or
migration's remove_migration_pte() must stop peeking for is_swap_entry()
before it takes pagetable lock.Consensus chooses the latter: we prefer to add overhead to migration
than to mremapping, which gets used by JVMs and by exec stack setup.Reported-and-tested-by: Paweł Sikora
Signed-off-by: Hugh Dickins
Acked-by: Andrea Arcangeli
Acked-by: Mel Gorman
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds
28 Sep, 2011
3 commits
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Discarding slab should be done when node partial > min_partial. Otherwise,
node partial slab may eat up all memory.Signed-off-by: Alex Shi
Acked-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Correct comment errors, that mistake cpu partial objects number as pages
number, may make reader misunderstand.Signed-off-by: Alex Shi
Reviewed-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Historically /proc/slabinfo and files under /sys/kernel/slab/* have
world read permissions and are accessible to the world. slabinfo
contains rather private information related both to the kernel and
userspace tasks. Depending on the situation, it might reveal either
private information per se or information useful to make another
targeted attack. Some examples of what can be learned by
reading/watching for /proc/slabinfo entries:1) dentry (and different *inode*) number might reveal other processes fs
activity. The number of dentry "active objects" doesn't strictly show
file count opened/touched by a process, however, there is a good
correlation between them. The patch "proc: force dcache drop on
unauthorized access" relies on the privacy of dentry count.2) different inode entries might reveal the same information as (1), but
these are more fine granted counters. If a filesystem is mounted in a
private mount point (or even a private namespace) and fs type differs from
other mounted fs types, fs activity in this mount point/namespace is
revealed. If there is a single ecryptfs mount point, the whole fs
activity of a single user is revealed. Number of files in ecryptfs
mount point is a private information per se.3) fuse_* reveals number of files / fs activity of a user in a user
private mount point. It is approx. the same severity as ecryptfs
infoleak in (2).4) sysfs_dir_cache similar to (2) reveals devices' addition/removal,
which can be otherwise hidden by "chmod 0700 /sys/". With 0444 slabinfo
the precise number of sysfs files is known to the world.5) buffer_head might reveal some kernel activity. With other
information leaks an attacker might identify what specific kernel
routines generate buffer_head activity.6) *kmalloc* infoleaks are very situational. Attacker should watch for
the specific kmalloc size entry and filter the noise related to the unrelated
kernel activity. If an attacker has relatively silent victim system, he
might get rather precise counters.Additional information sources might significantly increase the slabinfo
infoleak benefits. E.g. if an attacker knows that the processes
activity on the system is very low (only core daemons like syslog and
cron), he may run setxid binaries / trigger local daemon activity /
trigger network services activity / await sporadic cron jobs activity
/ etc. and get rather precise counters for fs and network activity of
these privileged tasks, which is unknown otherwise.Also hiding slabinfo and /sys/kernel/slab/* is a one step to complicate
exploitation of kernel heap overflows (and possibly, other bugs). The
related discussion:http://thread.gmane.org/gmane.linux.kernel/1108378
To keep compatibility with old permission model where non-root
monitoring daemon could watch for kernel memleaks though slabinfo one
should do:groupadd slabinfo
usermod -a -G slabinfo $MONITOR_USERAnd add the following commands to init scripts (to mountall.conf in
Ubuntu's upstart case):chmod g+r /proc/slabinfo /sys/kernel/slab/*/*
chgrp slabinfo /proc/slabinfo /sys/kernel/slab/*/*Signed-off-by: Vasiliy Kulikov
Reviewed-by: Kees Cook
Reviewed-by: Dave Hansen
Acked-by: Christoph Lameter
Acked-by: David Rientjes
CC: Valdis.Kletnieks@vt.edu
CC: Linus Torvalds
CC: Alan Cox
Signed-off-by: Pekka Enberg
22 Sep, 2011
1 commit
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* 'for-linus' of git://git.kernel.dk/linux-block:
floppy: use del_timer_sync() in init cleanup
blk-cgroup: be able to remove the record of unplugged device
block: Don't check QUEUE_FLAG_SAME_COMP in __blk_complete_request
mm: Add comment explaining task state setting in bdi_forker_thread()
mm: Cleanup clearing of BDI_pending bit in bdi_forker_thread()
block: simplify force plug flush code a little bit
block: change force plug flush call order
block: Fix queue_flag update when rq_affinity goes from 2 to 1
block: separate priority boosting from REQ_META
block: remove READ_META and WRITE_META
xen-blkback: fixed indentation and comments
xen-blkback: Don't disconnect backend until state switched to XenbusStateClosed.
19 Sep, 2011
2 commits
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* 'slab/urgent' of git://github.com/penberg/linux:
slub: add slab with one free object to partial list tail
15 Sep, 2011
9 commits
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Fast-forward merge with Linus to be able to merge patches
based on more recent version of the tree. -
Signed-off-by: Joe Perches
Acked-by: Paul Menage
Signed-off-by: Jiri Kosina -
The found entries by find_get_pages() could be all swap entries. In
this case we skip the entries, but make sure the skipped entries are
accounted, so we don't keep looping.Using nr_found > nr_skip to simplify code as suggested by Eric.
Reported-and-tested-by: Eric Dumazet
Signed-off-by: Shaohua Li
Signed-off-by: Linus Torvalds -
Xen backend drivers (e.g., blkback and netback) would sometimes fail to
map grant pages into the vmalloc address space allocated with
alloc_vm_area(). The GNTTABOP_map_grant_ref would fail because Xen could
not find the page (in the L2 table) containing the PTEs it needed to
update.(XEN) mm.c:3846:d0 Could not find L1 PTE for address fbb42000
netback and blkback were making the hypercall from a kernel thread where
task->active_mm != &init_mm and alloc_vm_area() was only updating the page
tables for init_mm. The usual method of deferring the update to the page
tables of other processes (i.e., after taking a fault) doesn't work as a
fault cannot occur during the hypercall.This would work on some systems depending on what else was using vmalloc.
Fix this by reverting ef691947d8a3 ("vmalloc: remove vmalloc_sync_all()
from alloc_vm_area()") and add a comment to explain why it's needed.Signed-off-by: David Vrabel
Cc: Jeremy Fitzhardinge
Cc: Konrad Rzeszutek Wilk
Cc: Ian Campbell
Cc: Keir Fraser
Cc: [3.0.x]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Revert the post-3.0 commit 82f9d486e59f5 ("memcg: add
memory.vmscan_stat").The implementation of per-memcg reclaim statistics violates how memcg
hierarchies usually behave: hierarchically.The reclaim statistics are accounted to child memcgs and the parent
hitting the limit, but not to hierarchy levels in between. Usually,
hierarchical statistics are perfectly recursive, with each level
representing the sum of itself and all its children.Since this exports statistics to userspace, this may lead to confusion
and problems with changing things after the release, so revert it now,
we can try again later.Signed-off-by: Johannes Weiner
Acked-by: KAMEZAWA Hiroyuki
Cc: Daisuke Nishimura
Cc: Michal Hocko
Cc: Ying Han
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Without swap, anonymous pages are not scanned. As such, they should not
count when considering force-scanning a small target if there is no swap.Otherwise, targets are not force-scanned even when their effective scan
number is zero and the other conditions--kswapd/memcg--apply.This fixes 246e87a93934 ("memcg: fix get_scan_count() for small
targets").[akpm@linux-foundation.org: fix comment]
Signed-off-by: Johannes Weiner
Acked-by: KAMEZAWA Hiroyuki
Reviewed-by: Michal Hocko
Cc: Ying Han
Cc: Balbir Singh
Cc: KOSAKI Motohiro
Cc: Daisuke Nishimura
Acked-by: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The vmstat_text array is only defined for CONFIG_SYSFS or CONFIG_PROC_FS,
yet it is referenced for per-node vmstat with CONFIG_NUMA:drivers/built-in.o: In function `node_read_vmstat':
node.c:(.text+0x1106df): undefined reference to `vmstat_text'Introduced in commit fa25c503dfa2 ("mm: per-node vmstat: show proper
vmstats").Define the array for CONFIG_NUMA as well.
[akpm@linux-foundation.org: remove unneeded ifdefs]
Signed-off-by: David Rientjes
Reported-by: Cong Wang
Acked-by: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When compiling mm/mempolicy.c with struct user copy checks the following
warning is shown:In file included from arch/x86/include/asm/uaccess.h:572,
from include/linux/uaccess.h:5,
from include/linux/highmem.h:7,
from include/linux/pagemap.h:10,
from include/linux/mempolicy.h:70,
from mm/mempolicy.c:68:
In function `copy_from_user',
inlined from `compat_sys_get_mempolicy' at mm/mempolicy.c:1415:
arch/x86/include/asm/uaccess_64.h:64: warning: call to `copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct
LD mm/built-in.oFix this by passing correct buffer size value.
Signed-off-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
commit 9d8cebd4bcd7 ("mm: fix mbind vma merge problem") didn't really
fix the mbind vma merge problem due to wrong pgoff value passing to
vma_merge(), which made vma_merge() always return NULL.Before the patch applied, we are getting a result like:
addr = 0x7fa58f00c000
[snip]
7fa58f00c000-7fa58f00d000 rw-p 00000000 00:00 0
7fa58f00d000-7fa58f00e000 rw-p 00000000 00:00 0
7fa58f00e000-7fa58f00f000 rw-p 00000000 00:00 0here 7fa58f00c000->7fa58f00f000 we get 3 VMAs which are expected to be
merged described as described in commit 9d8cebd.Re-testing the patched kernel with the reproducer provided in commit
9d8cebd, we get the correct result:addr = 0x7ffa5aaa2000
[snip]
7ffa5aaa2000-7ffa5aaa6000 rw-p 00000000 00:00 0
7fffd556f000-7fffd5584000 rw-p 00000000 00:00 0 [stack]Signed-off-by: Caspar Zhang
Cc: KOSAKI Motohiro
Cc: Christoph Lameter
Cc: Hugh Dickins
Cc: Mel Gorman
Cc: Lee Schermerhorn
Cc: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Sep, 2011
1 commit
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I find a way to reduce a variable in get_partial_node(). That is also helpful
for code understanding.Acked-by: Christoph Lameter
Signed-off-by: Alex Shi
Signed-off-by: Pekka Enberg
03 Sep, 2011
2 commits
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CC: Wu Fengguang
CC: Andrew Morton
Signed-off-by: Jan Kara
Signed-off-by: Jens Axboe -
bdi_forker_thread() clears BDI_pending bit at the end of the main loop.
However clearing of this bit must not be done in some cases which is
handled by calling 'continue' from switch statement. That's kind of
unusual construct and without a good reason so change the function into
more intuitive code flow.CC: Wu Fengguang
CC: Andrew Morton
Signed-off-by: Jan Kara
Signed-off-by: Jens Axboe
27 Aug, 2011
2 commits
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Adding slab to partial list head/tail is sensitive to performance.
So explicitly uses DEACTIVATE_TO_TAIL/DEACTIVATE_TO_HEAD to document
it to avoid we get it wrong.Acked-by: Christoph Lameter
Signed-off-by: Shaohua Li
Signed-off-by: Shaohua Li
Signed-off-by: Pekka Enberg -
The slab has just one free object, adding it to partial list head doesn't make
sense. And it can cause lock contentation. For example,
1. CPU takes the slab from partial list
2. fetch an object
3. switch to another slab
4. free an object, then the slab is added to partial list again
In this way n->list_lock will be heavily contended.
In fact, Alex had a hackbench regression. 3.1-rc1 performance drops about 70%
against 3.0. This patch fixes it.Acked-by: Christoph Lameter
Reported-by: Alex Shi
Signed-off-by: Shaohua Li
Signed-off-by: Shaohua Li
Signed-off-by: Pekka Enberg
26 Aug, 2011
5 commits
-
Commit 79dfdaccd1d5 ("memcg: make oom_lock 0 and 1 based rather than
counter") tried to oom lock the hierarchy and roll back upon
encountering an already locked memcg.The code is confused when it comes to detecting a locked memcg, though,
so it would fail and rollback after locking one memcg and encountering
an unlocked second one.The result is that oom-locking hierarchies fails unconditionally and
that every oom killer invocation simply goes to sleep on the oom
waitqueue forever. The tasks practically hang forever without anyone
intervening, possibly holding locks that trip up unrelated tasks, too.Signed-off-by: Johannes Weiner
Acked-by: Michal Hocko
Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
ZONE_CONGESTED is only cleared in kswapd, but pages can be freed in any
task. It's possible ZONE_CONGESTED isn't cleared in some cases:1. the zone is already balanced just entering balance_pgdat() for
order-0 because concurrent tasks free memory. In this case, later
check will skip the zone as it's balanced so the flag isn't cleared.2. high order balance fallbacks to order-0. quote from Mel: At the
end of balance_pgdat(), kswapd uses the following logic;If reclaiming at high order {
for each zone {
if all_unreclaimable
skip
if watermark is not met
order = 0
loop again/* watermark is met */
clear congested
}
}i.e. it clears ZONE_CONGESTED if it the zone is balanced. if not,
it restarts balancing at order-0. However, if the higher zones are
balanced for order-0, kswapd will miss clearing ZONE_CONGESTED as
that only happens after a zone is shrunk. This can mean that
wait_iff_congested() stalls unnecessarily.This patch makes kswapd clear ZONE_CONGESTED during its initial
highmem->dma scan for zones that are already balanced.Signed-off-by: Shaohua Li
Acked-by: Mel Gorman
Reviewed-by: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
I get the below warning:
BUG: using smp_processor_id() in preemptible [00000000] code: bash/746
caller is native_sched_clock+0x37/0x6e
Pid: 746, comm: bash Tainted: G W 3.0.0+ #254
Call Trace:
[] debug_smp_processor_id+0xc2/0xdc
[] native_sched_clock+0x37/0x6e
[] try_to_free_mem_cgroup_pages+0x7d/0x270
[] mem_cgroup_force_empty+0x24b/0x27a
[] ? sys_close+0x38/0x138
[] ? sys_close+0x38/0x138
[] mem_cgroup_force_empty_write+0x17/0x19
[] cgroup_file_write+0xa8/0xba
[] vfs_write+0xb3/0x138
[] sys_write+0x4a/0x71
[] ? sys_close+0xf0/0x138
[] system_call_fastpath+0x16/0x1bsched_clock() can't be used with preempt enabled. And we don't need
fast approach to get clock here, so let's use ktime API.Signed-off-by: Shaohua Li
Acked-by: KAMEZAWA Hiroyuki
Tested-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Commit d1a05b6973c7 ("memcg do not try to drain per-cpu caches without
pages") added a drain_local_stock() call to a preemptible section.The draining task looks up the cpu-local stock twice to set the
draining-flag, then to drain the stock and clear the flag again. If the
task is migrated to a different CPU in between, noone will clear the
flag on the first stock and it will be forever undrainable. Its charge
can not be recovered and the cgroup can not be deleted anymore.Properly pin the task to the executing CPU while draining stocks.
Signed-off-by: Johannes Weiner
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
* 'urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback:
squeeze max-pause area and drop pass-good area
24 Aug, 2011
1 commit
-
Signed-off-by: Justin P. Mattock
Signed-off-by: Jiri Kosina
20 Aug, 2011
6 commits
-
Allow filling out the rest of the kmem_cache_cpu cacheline with pointers to
partial pages. The partial page list is used in slab_free() to avoid
per node lock taking.In __slab_alloc() we can then take multiple partial pages off the per
node partial list in one go reducing node lock pressure.We can also use the per cpu partial list in slab_alloc() to avoid scanning
partial lists for pages with free objects.The main effect of a per cpu partial list is that the per node list_lock
is taken for batches of partial pages instead of individual ones.Potential future enhancements:
1. The pickup from the partial list could be perhaps be done without disabling
interrupts with some work. The free path already puts the page into the
per cpu partial list without disabling interrupts.2. __slab_free() may have some code paths that could use optimization.
Performance:
Before After
./hackbench 100 process 200000
Time: 1953.047 1564.614
./hackbench 100 process 20000
Time: 207.176 156.940
./hackbench 100 process 20000
Time: 204.468 156.940
./hackbench 100 process 20000
Time: 204.879 158.772
./hackbench 10 process 20000
Time: 20.153 15.853
./hackbench 10 process 20000
Time: 20.153 15.986
./hackbench 10 process 20000
Time: 19.363 16.111
./hackbench 1 process 20000
Time: 2.518 2.307
./hackbench 1 process 20000
Time: 2.258 2.339
./hackbench 1 process 20000
Time: 2.864 2.163Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
There is no need anymore to return the pointer to a slab page from get_partial()
since the page reference can be stored in the kmem_cache_cpu structures "page" field.Return an object pointer instead.
That in turn allows a simplification of the spaghetti code in __slab_alloc().
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Pass the kmem_cache_cpu pointer to get_partial(). That way
we can avoid the this_cpu_write() statements.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
inuse will always be set to page->objects. There is no point in
initializing the field to zero in new_slab() and then overwriting
the value in __slab_alloc().Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
Two statements in __slab_alloc() do not have any effect.
1. c->page is already set to NULL by deactivate_slab() called right before.
2. gfpflags are masked in new_slab() before being passed to the page
allocator. There is no need to mask gfpflags in __slab_alloc in particular
since most frequent processing in __slab_alloc does not require the use of a
gfpmask.Cc: torvalds@linux-foundation.org
Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg -
There are two situations in which slub holds a lock while releasing
pages:A. During kmem_cache_shrink()
B. During kmem_cache_close()For A build a list while holding the lock and then release the pages
later. In case of B we are the last remaining user of the slab so
there is no need to take the listlock.After this patch all calls to the page allocator to free pages are
done without holding any spinlocks. kmem_cache_destroy() will still
hold the slub_lock semaphore.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
19 Aug, 2011
1 commit
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Revert the pass-good area introduced in ffd1f609ab10 ("writeback:
introduce max-pause and pass-good dirty limits") and make the max-pause
area smaller and safe.This fixes ~30% performance regression in the ext3 data=writeback
fio_mmap_randwrite_64k/fio_mmap_randrw_64k test cases, where there are
12 JBOD disks, on each disk runs 8 concurrent tasks doing reads+writes.Using deadline scheduler also has a regression, but not that big as CFQ,
so this suggests we have some write starvation.The test logs show that
- the disks are sometimes under utilized
- global dirty pages sometimes rush high to the pass-good area for
several hundred seconds, while in the mean time some bdi dirty pages
drop to very low value (bdi_dirty << bdi_thresh). Then suddenly the
global dirty pages dropped under global dirty threshold and bdi_dirty
rush very high (for example, 2 times higher than bdi_thresh). During
which time balance_dirty_pages() is not called at all.So the problems are
1) The random writes progress so slow that they break the assumption of
the max-pause logic that "8 pages per 200ms is typically more than
enough to curb heavy dirtiers".2) The max-pause logic ignored task_bdi_thresh and thus opens the possibility
for some bdi's to over dirty pages, leading to (bdi_dirty >> bdi_thresh)
and then (bdi_thresh >> bdi_dirty) for others.3) The higher max-pause/pass-good thresholds somehow leads to the bad
swing of dirty pages.The fix is to allow the task to slightly dirty over task_bdi_thresh, but
no way to exceed bdi_dirty and/or global dirty_thresh.Tests show that it fixed the JBOD regression completely (both behavior
and performance), while still being able to cut down large pause times
in balance_dirty_pages() for single-disk cases.Reported-by: Li Shaohua
Tested-by: Li Shaohua
Acked-by: Jan Kara
Signed-off-by: Wu Fengguang
18 Aug, 2011
1 commit
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Followup to 33dd4e0ec911 "mm: make some struct page's const" which missed the
HASHED_PAGE_VIRTUAL case.Signed-off-by: Ian Campbell
Cc: Andrea Arcangeli
Cc: Rik van Riel
Cc: Michel Lespinasse
Cc: Mel Gorman
Cc: Andrew Morton
Signed-off-by: Linus Torvalds
