- Sep 10, 2010
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Tejun Heo authored
Percpu allocator should clear memory before returning it but the km allocator forgot to do it. Fix it. Signed-off-by:
Tejun Heo <tj@kernel.org> Reported-by:
Peter Zijlstra <peterz@infradead.org> Acked-by:
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- Sep 09, 2010
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Tejun Heo authored
Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by:
Sachin Sant <sachinp@in.ibm.com>
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- Sep 08, 2010
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Tejun Heo authored
On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by:
Christoph Lameter <cl@linux-foundation.org> Acked-by:
Pekka Enberg <penberg@cs.helsinki.fi>
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Tejun Heo authored
These functions are used only by percpu memory allocator on SMP. Don't build them on UP. Signed-off-by:
Chrsitoph Lameter <cl@linux.com>
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- Aug 28, 2010
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Hugh Dickins authored
After several hours, kbuild tests hang with anon_vma_prepare() spinning on a newly allocated anon_vma's lock - on a box with CONFIG_TREE_PREEMPT_RCU=y (which makes this very much more likely, but it could happen without). The ever-subtle page_lock_anon_vma() now needs a further twist: since anon_vma_prepare() and anon_vma_fork() are liable to change the ->root of a reused anon_vma structure at any moment, page_lock_anon_vma() needs to check page_mapped() again before succeeding, otherwise page_unlock_anon_vma() might address a different root->lock. Signed-off-by:
Hugh Dickins <hughd@google.com> Reviewed-by:
Rik van Riel <riel@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- Aug 27, 2010
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Namhyung Kim authored
When pcpu_build_alloc_info() searches best_upa value, it ignores current value if the number of waste units exceeds 1/3 of the number of total cpus. But the comment on the code says that it will ignore if wastage is over 25%. Modify the comment. Signed-off-by:
Namhyung Kim <namhyung@gmail.com> Signed-off-by:
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Huang Shijie authored
The original code did not free the old map. This patch fixes it. tj: use @old as memcpy source instead of @chunk->map, and indentation and description update Signed-off-by:Huang Shijie <shijie8@gmail.com> Signed-off-by:
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- Aug 24, 2010
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Tony Luck authored
pa-risc and ia64 have stacks that grow upwards. Check that they do not run into other mappings. By making VM_GROWSUP 0x0 on architectures that do not ever use it, we can avoid some unpleasant #ifdefs in check_stack_guard_page(). Signed-off-by:
Tony Luck <tony.luck@intel.com> Signed-off-by:
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Dave Chinner authored
I noticed XFS writeback in 2.6.36-rc1 was much slower than it should have been. Enabling writeback tracing showed: flush-253:16-8516 [007] 1342952.351608: wbc_writepage: bdi 253:16: towrt=1024 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [007] 1342952.351654: wbc_writepage: bdi 253:16: towrt=1023 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369520: wbc_writepage: bdi 253:16: towrt=0 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369542: wbc_writepage: bdi 253:16: towrt=-1 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369549: wbc_writepage: bdi 253:16: towrt=-2 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 Writeback is not terminating in background writeback if ->writepage is returning with wbc->nr_to_write == 0, resulting in sub-optimal single page writeback on XFS. Fix the write_cache_pages loop to terminate correctly when this situation occurs and so prevent this sub-optimal background writeback pattern. This improves sustained sequential buffered write performance from around 250MB/s to 750MB/s for a 100GB file on an XFS filesystem on my 8p test VM. Cc:<stable@kernel.org> Signed-off-by:Dave Chinner <dchinner@redhat.com> Reviewed-by:
Wu Fengguang <fengguang.wu@intel.com> Reviewed-by:
Christoph Hellwig <hch@lst.de>
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- Aug 22, 2010
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Michael Rubin authored
This allows code outside of the mm core to safely manipulate page state and not worry about the other accounting. Not using these routines means that some code will lose track of the accounting and we get bugs. This has happened once already. Signed-off-by:
Michael Rubin <mrubin@google.com> Signed-off-by:
Sage Weil <sage@newdream.net>
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- Aug 21, 2010
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Linus Torvalds authored
Like the mlock() change previously, this makes the stack guard check code use vma->vm_prev to see what the mapping below the current stack is, rather than have to look it up with find_vma(). Also, accept an abutting stack segment, since that happens naturally if you split the stack with mlock or mprotect. Tested-by:
Ian Campbell <ijc@hellion.org.uk> Signed-off-by:
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Linus Torvalds authored
If we've split the stack vma, only the lowest one has the guard page. Now that we have a doubly linked list of vma's, checking this is trivial. Tested-by:
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Linus Torvalds authored
It's a really simple list, and several of the users want to go backwards in it to find the previous vma. So rather than have to look up the previous entry with 'find_vma_prev()' or something similar, just make it doubly linked instead. Tested-by:
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- Aug 20, 2010
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KOSAKI Motohiro authored
dump_tasks() needs to hold the RCU read lock around its access of the target task's UID. To this end it should use task_uid() as it only needs that one thing from the creds. The fact that dump_tasks() holds tasklist_lock is insufficient to prevent the target process replacing its credentials on another CPU. Then, this patch change to call rcu_read_lock() explicitly. =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- mm/oom_kill.c:410 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 4 locks held by kworker/1:2/651: #0: (events){+.+.+.}, at: [<ffffffff8106aae7>] process_one_work+0x137/0x4a0 #1: (moom_work){+.+...}, at: [<ffffffff8106aae7>] process_one_work+0x137/0x4a0 #2: (tasklist_lock){.+.+..}, at: [<ffffffff810fafd4>] out_of_memory+0x164/0x3f0 #3: (&(&p->alloc_lock)->rlock){+.+...}, at: [<ffffffff810fa48e>] find_lock_task_mm+0x2e/0x70 Signed-off-by:KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by:
David Howells <dhowells@redhat.com> Acked-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by:
David Rientjes <rientjes@google.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
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KOSAKI Motohiro authored
Commit 0aad4b31 ("oom: fold __out_of_memory into out_of_memory") introduced a tasklist_lock leak. Then it caused following obvious danger warnings and panic. ================================================ [ BUG: lock held when returning to user space! ] ------------------------------------------------ rsyslogd/1422 is leaving the kernel with locks still held! 1 lock held by rsyslogd/1422: #0: (tasklist_lock){.+.+.+}, at: [<ffffffff810faf64>] out_of_memory+0x164/0x3f0 BUG: scheduling while atomic: rsyslogd/1422/0x00000002 INFO: lockdep is turned off. This patch fixes it. Signed-off-by:
Minchan Kim <minchan.kim@gmail.com> Acked-by:
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KOSAKI Motohiro authored
Commit b940fd70 ("oom: remove unnecessary code and cleanup") added an unnecessary NULL pointer dereference. remove it. Signed-off-by:
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Jan Kara authored
When radix_tree_maxindex() is ~0UL, it can happen that scanning overflows index and tree traversal code goes astray reading memory until it hits unreadable memory. Check for overflow and exit in that case. Signed-off-by:
Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@lst.de> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by:
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- Aug 18, 2010
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Hugh Dickins authored
list_add() corruption messages reported from shmem_fill_super()'s recently introduced percpu_counter_init(): shmem_put_super() needs to remember to percpu_counter_destroy(). And also check error from percpu_counter_init(). Reported-bisected-and-tested-by:
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by:
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- Aug 15, 2010
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Linus Torvalds authored
This commit makes the stack guard page somewhat less visible to user space. It does this by: - not showing the guard page in /proc/<pid>/maps It looks like lvm-tools will actually read /proc/self/maps to figure out where all its mappings are, and effectively do a specialized "mlockall()" in user space. By not showing the guard page as part of the mapping (by just adding PAGE_SIZE to the start for grows-up pages), lvm-tools ends up not being aware of it. - by also teaching the _real_ mlock() functionality not to try to lock the guard page. That would just expand the mapping down to create a new guard page, so there really is no point in trying to lock it in place. It would perhaps be nice to show the guard page specially in /proc/<pid>/maps (or at least mark grow-down segments some way), but let's not open ourselves up to more breakage by user space from programs that depends on the exact deails of the 'maps' file. Special thanks to Henrique de Moraes Holschuh for diving into lvm-tools source code to see what was going on with the whole new warning. Reported-and-tested-by:
François Valenduc <francois.valenduc@tvcablenet.be> Reported-by:
Henrique de Moraes Holschuh <hmh@hmh.eng.br> Cc: stable@kernel.org Signed-off-by:
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- Aug 14, 2010
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Randy Dunlap authored
Remove leading /** from non-kernel-doc function comments to prevent kernel-doc warnings. Signed-off-by:
Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by:
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Linus Torvalds authored
We do in fact need to unmap the page table _before_ doing the whole stack guard page logic, because if it is needed (mainly 32-bit x86 with PAE and CONFIG_HIGHPTE, but other architectures may use it too) then it will do a kmap_atomic/kunmap_atomic. And those kmaps will create an atomic region that we cannot do allocations in. However, the whole stack expand code will need to do anon_vma_prepare() and vma_lock_anon_vma() and they cannot do that in an atomic region. Now, a better model might actually be to do the anon_vma_prepare() when _creating_ a VM_GROWSDOWN segment, and not have to worry about any of this at page fault time. But in the meantime, this is the straightforward fix for the issue. See https://bugzilla.kernel.org/show_bug.cgi?id=16588 for details. Reported-by:
Wylda <wylda@volny.cz> Reported-by:
Sedat Dilek <sedat.dilek@gmail.com> Reported-by:
Mike Pagano <mpagano@gentoo.org> Reported-by:
Ed Tomlinson <edt@aei.ca> Cc: Pekka Enberg <penberg@kernel.org> Cc: Greg KH <gregkh@suse.de> Cc: stable@kernel.org Signed-off-by:
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- Aug 13, 2010
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David Howells authored
Remove an extraneous no_printk() in mm/nommu.c that got missed when the function got generalised from several things that used it in commit 12fdff3f ("Add a dummy printk function for the maintenance of unused printks"). Without this, the following error is observed: mm/nommu.c:41: error: conflicting types for 'no_printk' include/linux/kernel.h:314: error: previous definition of 'no_printk' was here Reported-by:
Michal Simek <monstr@monstr.eu> Signed-off-by:
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Linus Torvalds authored
.. which didn't show up in my tests because it's a no-op on x86-64 and most other architectures. But we enter the function with the last-level page table mapped, and should unmap it at exit. Signed-off-by: -
Linus Torvalds authored
This is a rather minimally invasive patch to solve the problem of the user stack growing into a memory mapped area below it. Whenever we fill the first page of the stack segment, expand the segment down by one page. Now, admittedly some odd application might _want_ the stack to grow down into the preceding memory mapping, and so we may at some point need to make this a process tunable (some people might also want to have more than a single page of guarding), but let's try the minimal approach first. Tested with trivial application that maps a single page just below the stack, and then starts recursing. Without this, we will get a SIGSEGV _after_ the stack has smashed the mapping. With this patch, we'll get a nice SIGBUS just as the stack touches the page just above the mapping. Requested-by:
Keith Packard <keithp@keithp.com> Signed-off-by:
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- Aug 12, 2010
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Wu Fengguang authored
Document global_dirty_limits() and bdi_dirty_limit(). Signed-off-by:
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Wu Fengguang authored
Split get_dirty_limits() into global_dirty_limits()+bdi_dirty_limit(), so that the latter can be avoided when under global dirty background threshold (which is the normal state for most systems). Signed-off-by:
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Wu Fengguang authored
Reducing the number of times balance_dirty_pages calls global_page_state reduces the cache references and so improves write performance on a variety of workloads. 'perf stats' of simple fio write tests shows the reduction in cache access. Where the test is fio 'write,mmap,600Mb,pre_read' on AMD AthlonX2 with 3Gb memory (dirty_threshold approx 600 Mb) running each test 10 times, dropping the fasted & slowest values then taking the average & standard deviation average (s.d.) in millions (10^6) 2.6.31-rc8 648.6 (14.6) +patch 620.1 (16.5) Achieving this reduction is by dropping clip_bdi_dirty_limit as it rereads the counters to apply the dirty_threshold and moving this check up into balance_dirty_pages where it has already read the counters. Also by rearrange the for loop to only contain one copy of the limit tests allows the pdflush test after the loop to use the local copies of the counters rather than rereading them. In the common case with no throttling it now calls global_page_state 5 fewer times and bdi_stat 2 fewer. Fengguang: This patch slightly changes behavior by replacing clip_bdi_dirty_limit() with the explicit check (nr_reclaimable + nr_writeback >= dirty_thresh) to avoid exceeding the dirty limit. Since the bdi dirty limit is mostly accurate we don't need to do routinely clip. A simple dirty limit check would be enough. The check is necessary because, in principle we should throttle everything calling balance_dirty_pages() when we're over the total limit, as said by Peter. We now set and clear dirty_exceeded not only based on bdi dirty limits, but also on the global dirty limit. The global limit check is added in place of clip_bdi_dirty_limit() for safety and not intended as a behavior change. The bdi limits should be tight enough to keep all dirty pages under the global limit at most time; occasional small exceeding should be OK though. The change makes the logic more obvious: the global limit is the ultimate goal and shall be always imposed. We may now start background writeback work based on outdated conditions. That's safe because the bdi flush thread will (and have to) double check the states. It reduces overall overheads because the test based on old states still have good chance to be right. [akpm@linux-foundation.org] fix uninitialized dirty_exceeded Signed-off-by:
Richard Kennedy <richard@rsk.demon.co.uk> Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by:
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Randy Dunlap authored
Fix a fatal kernel-doc error due to a #define coming between a function's kernel-doc notation and the function signature. (kernel-doc cannot handle this) Signed-off-by:
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- Aug 11, 2010
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KOSAKI Motohiro authored
We have zone_to_nid(). this patch convert all existing users of zone->zone_pgdat->node_id. Signed-off-by:
Balbir Singh <balbir@linux.vnet.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Nishimura Daisuke <d-nishimura@mtf.biglobe.ne.jp> Signed-off-by:
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KOSAKI Motohiro authored
mem_cgroup_soft_limit_reclaim() has zone, nid and zid argument. but nid and zid can be calculated from zone. So remove it. Signed-off-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by:
Mel Gorman <mel@csn.ul.ie> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Nishimura Daisuke <d-nishimura@mtf.biglobe.ne.jp> Signed-off-by:
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KOSAKI Motohiro authored
Currently mem_cgroup_shrink_node_zone() call shrink_zone() directly. thus it doesn't need to initialize sc.nodemask because shrink_zone() doesn't use it at all. Signed-off-by:
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KOSAKI Motohiro authored
sc.nr_reclaimed and sc.nr_scanned have already been initialized few lines above "struct scan_control sc = {}" statement. So, This patch remove this unnecessary code. Signed-off-by: -
KOSAKI Motohiro authored
Currently, mem_cgroup_shrink_node_zone() initialize sc.nr_to_reclaim as 0. It mean shrink_zone() only scan 32 pages and immediately return even if it doesn't reclaim any pages. This patch fixes it. Signed-off-by:
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KAMEZAWA Hiroyuki authored
Now, memory cgroup increments css(cgroup subsys state)'s reference count per a charged page. And the reference count is kept until the page is uncharged. But this has 2 bad effect. 1. Because css_get/put calls atomic_inc()/dec, heavy call of them on large smp will not scale well. 2. Because css's refcnt cannot be in a state as "ready-to-release", cgroup's notify_on_release handler can't work with memcg. 3. css's refcnt is atomic_t, it means smaller than 32bit. Maybe too small. This has been a problem since the 1st merge of memcg. This is a trial to remove css's refcnt per a page. Even if we remove refcnt, pre_destroy() does enough synchronization as - check res->usage == 0. - check no pages on LRU. This patch removes css's refcnt per page. Even after this patch, at the 1st look, it seems css_get() is still called in try_charge(). But the logic is. - If a memcg of mm->owner is cached one, consume_stock() will work. At success, return immediately. - If consume_stock returns false, css_get() is called and go to slow path which may be blocked. At the end of slow path, css_put() is called and restart from the start if necessary. So, in the fast path, we don't call css_get() and can avoid access to shared counter. This patch can make the most possible case fast. Here is a result of multi-threaded page fault benchmark. [Before] 25.32% multi-fault-all [kernel.kallsyms] [k] clear_page_c 9.30% multi-fault-all [kernel.kallsyms] [k] _raw_spin_lock_irqsave 8.02% multi-fault-all [kernel.kallsyms] [k] try_get_mem_cgroup_from_mm <=====(*) 7.83% multi-fault-all [kernel.kallsyms] [k] down_read_trylock 5.38% multi-fault-all [kernel.kallsyms] [k] __css_put 5.29% multi-fault-all [kernel.kallsyms] [k] __alloc_pages_nodemask 4.92% multi-fault-all [kernel.kallsyms] [k] _raw_spin_lock_irq 4.24% multi-fault-all [kernel.kallsyms] [k] up_read 3.53% multi-fault-all [kernel.kallsyms] [k] css_put 2.11% multi-fault-all [kernel.kallsyms] [k] handle_mm_fault 1.76% multi-fault-all [kernel.kallsyms] [k] __rmqueue 1.64% multi-fault-all [kernel.kallsyms] [k] __mem_cgroup_commit_charge [After] 28.41% multi-fault-all [kernel.kallsyms] [k] clear_page_c 10.08% multi-fault-all [kernel.kallsyms] [k] _raw_spin_lock_irq 9.58% multi-fault-all [kernel.kallsyms] [k] down_read_trylock 9.38% multi-fault-all [kernel.kallsyms] [k] _raw_spin_lock_irqsave 5.86% multi-fault-all [kernel.kallsyms] [k] __alloc_pages_nodemask 5.65% multi-fault-all [kernel.kallsyms] [k] up_read 2.82% multi-fault-all [kernel.kallsyms] [k] handle_mm_fault 2.64% multi-fault-all [kernel.kallsyms] [k] mem_cgroup_add_lru_list 2.48% multi-fault-all [kernel.kallsyms] [k] __mem_cgroup_commit_charge Then, 8.02% of try_get_mem_cgroup_from_mm() disappears because this patch removes css_tryget() in it. (But yes, this is an extreme case.) Signed-off-by:Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by:
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KAMEZAWA Hiroyuki authored
When the OOM killer scans task, it check a task is under memcg or not when it's called via memcg's context. But, as Oleg pointed out, a thread group leader may have NULL ->mm and task_in_mem_cgroup() may do wrong decision. We have to use find_lock_task_mm() in memcg as generic OOM-Killer does. Signed-off-by:
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Daisuke Nishimura authored
mem_cgroup_charge_common() is always called with @mem = NULL, so it's meaningless. This patch removes it. Signed-off-by:
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Daisuke Nishimura authored
- try_get_mem_cgroup_from_mm() calls rcu_read_lock/unlock by itself, so we don't have to call them in task_in_mem_cgroup(). - *mz is not used in __mem_cgroup_uncharge_common(). - we don't have to call lookup_page_cgroup() in mem_cgroup_end_migration() after we've cleared PCG_MIGRATION of @oldpage. - remove empty comment. - remove redundant empty line in mem_cgroup_cache_charge(). Signed-off-by:
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KAMEZAWA Hiroyuki authored
Now, for checking a memcg is under task-account-moving, we do css_tryget() against mc.to and mc.from. But this is just complicating things. This patch makes the check easier. This patch adds a spinlock to move_charge_struct and guard modification of mc.to and mc.from. By this, we don't have to think about complicated races arount this not-critical path. [balbir@linux.vnet.ibm.com: don't crash on a null memcg being passed] Signed-off-by:
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KAMEZAWA Hiroyuki authored
mem_cgroup_try_charge() has a big loop in it and seems to be hard to read. Most of routines are for slow path. This patch moves codes out from the loop and make it clear what's done. Summary: - refactoring a function to detect a memcg is under acccount move or not. - refactoring a function to wait for the end of moving task acct. - refactoring a main loop('s slow path) as a function and make it clear why we retry or quit by return code. - add fatal_signal_pending() check for bypassing charge loops. Signed-off-by: -
Naoya Horiguchi authored
This patch fixes possible deadlock in hugepage lock_page() by adding missing unlock_page(). libhugetlbfs test will hit this bug when the next patch in this patchset ("hugetlb, HWPOISON: move PG_HWPoison bit check") is applied. Signed-off-by:Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by:
Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Acked-by:
Andi Kleen <ak@linux.intel.com>
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