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Tejun Heo ccea34b5d0 percpu: finer grained locking to break deadlock and allow atomic free 
Impact: fix deadlock and allow atomic free

Percpu allocation always uses GFP_KERNEL and whole alloc/free paths
were protected by single mutex.  All percpu allocations have been from
GFP_KERNEL-safe context and the original allocator had this assumption
too.  However, by protecting both alloc and free paths with the same
mutex, the new allocator creates free -> alloc -> GFP_KERNEL
dependency which the original allocator didn't have.  This can lead to
deadlock if free is called from FS or IO paths.  Also, in general,
allocators are expected to allow free to be called from atomic
context.

This patch implements finer grained locking to break the deadlock and
allow atomic free.  For details, please read the "Synchronization
rules" comment.

While at it, also add CONTEXT: to function comments to describe which
context they expect to be called from and what they do to it.

This problem was reported by Thomas Gleixner and Peter Zijlstra.

  http://thread.gmane.org/gmane.linux.kernel/802384

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Peter Zijlstra <peterz@infradead.org>
 		2009-03-07 14:46:35 +09:00
..
Kconfig Remove obsolete CONFIG_RESOURCES_64BIT 2009-01-06 15:59:14 -08:00
Makefile percpu: implement new dynamic percpu allocator 2009-02-20 16:29:08 +09:00
allocpercpu.c percpu: kill percpu_alloc() and friends 2009-02-20 16:29:08 +09:00
backing-dev.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-01-06 17:10:04 -08:00
bootmem.c bootmem, x86: further fixes for arch-specific bootmem wrapping 2009-03-01 16:06:56 +09:00
bounce.c bounce: don't rely on a zeroed bio_vec list 2008-12-29 08:29:52 +01:00
dmapool.c
…
fadvise.c [CVE-2009-0029] System call wrapper special cases 2009-01-14 14:15:18 +01:00
failslab.c SLUB: failslab support 2008-12-29 11:27:46 +02:00
filemap.c x86, mm: dont use non-temporal stores in pagecache accesses 2009-03-02 11:06:49 +01:00
filemap_xip.c x86, mm: dont use non-temporal stores in pagecache accesses 2009-03-02 11:06:49 +01:00
fremap.c Do not account for the address space used by hugetlbfs using VM_ACCOUNT 2009-02-10 10:48:42 -08:00
highmem.c x86, pat: avoid highmem cache attribute aliasing 2008-08-15 17:22:57 +02:00
hugetlb.c Do not account for hugetlbfs quota at mmap() time if mapping [SHM|MAP]_NORESERVE 2009-02-11 12:38:09 -08:00
internal.h mm: make get_user_pages() interruptible 2009-01-06 15:59:08 -08:00
maccess.c
…
madvise.c [CVE-2009-0029] System call wrappers part 14 2009-01-14 14:15:24 +01:00
memcontrol.c memcg: NULL pointer dereference at rmdir on some NUMA systems 2009-01-29 18:04:44 -08:00
memory.c do_wp_page: fix regression with execute in place 2009-02-05 12:56:48 -08:00
memory_hotplug.c mm: remove GFP_HIGHUSER_PAGECACHE 2009-01-06 15:59:01 -08:00
mempolicy.c [CVE-2009-0029] System call wrappers part 28 2009-01-14 14:15:30 +01:00
mempool.c
…
migrate.c migration: migrate_vmas should check "vma" 2009-02-11 14:25:34 -08:00
mincore.c [CVE-2009-0029] System call wrappers part 14 2009-01-14 14:15:24 +01:00
mlock.c Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-02-17 14:27:39 -08:00
mm_init.c mm: mminit_loglevel cannot be __meminitdata anymore 2008-08-20 15:40:30 -07:00
mmap.c mm: rearrange exit_mmap() to unlock before arch_exit_mmap 2009-02-11 14:25:37 -08:00
mmu_notifier.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
mmzone.c mm: mark the correct zone as full when scanning zonelists 2008-09-13 14:41:52 -07:00
mprotect.c Do not account for the address space used by hugetlbfs using VM_ACCOUNT 2009-02-10 10:48:42 -08:00
mremap.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
msync.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
nommu.c uclinux: add process name to allocation error message 2009-01-27 16:42:03 +10:00
oom_kill.c memcg: avoid deadlock caused by race between oom and cpuset_attach 2009-01-08 08:31:09 -08:00
page-writeback.c mm: task dirty accounting fix 2009-02-18 15:37:54 -08:00
page_alloc.c mm: fix memmap init for handling memory hole 2009-02-18 15:37:55 -08:00
page_cgroup.c memcg: use __GFP_NOWARN in page cgroup allocation 2009-02-11 14:25:35 -08:00
page_io.c block: fix bad definition of BIO_RW_SYNC 2009-02-18 10:32:00 +01:00
page_isolation.c memory hotplug: fix page_zone() calculation in test_pages_isolated() 2008-11-06 15:41:19 -08:00
pagewalk.c pagemap: pass mm into pagewalkers 2008-06-12 18:05:41 -07:00
pdflush.c cpumask: convert mm/ 2009-01-01 10:12:29 +10:30
percpu.c percpu: finer grained locking to break deadlock and allow atomic free 2009-03-07 14:46:35 +09:00
prio_tree.c
…
quicklist.c mm: size of quicklists shouldn't be proportional to the number of CPUs 2008-09-02 19:21:38 -07:00
readahead.c vmscan: split LRU lists into anon & file sets 2008-10-20 08:50:25 -07:00
rmap.c mm: fix mlocked page counter mismatch 2009-02-11 14:25:35 -08:00
shmem.c shmem: fix shared anonymous accounting 2009-02-25 12:21:42 -08:00
shmem_acl.c [PATCH] sanitize ->permission() prototype 2008-07-26 20:53:14 -04:00
slab.c mm: Export symbol ksize() 2009-02-12 17:50:46 +02:00
slob.c mm: Export symbol ksize() 2009-02-12 17:50:46 +02:00
slub.c mm: Export symbol ksize() 2009-02-12 17:50:46 +02:00
sparse-vmemmap.c vmemmap: warn about page_structs with remote distance 2008-11-06 15:41:19 -08:00
sparse.c meminit section warnings 2008-11-30 10:03:35 -08:00
swap.c memcg: add zone_reclaim_stat 2009-01-08 08:31:08 -08:00
swap_state.c memcg: mem+swap controller core 2009-01-08 08:31:05 -08:00
swapfile.c PM/hibernate: fix "swap breaks after hibernation failures" 2009-02-21 14:17:17 -08:00
thrash.c
…
truncate.c mmap: handle mlocked pages during map, remap, unmap 2008-10-20 08:52:31 -07:00
util.c slab: introduce kzfree() 2009-02-20 17:57:48 -08:00
vmalloc.c Merge branch 'x86/core' into core/percpu 2009-03-04 02:29:19 +01:00
vmscan.c swsusp: clean up shrink_all_zones() 2009-02-21 14:17:17 -08:00
vmstat.c cpumask: convert mm/ 2009-01-01 10:12:29 +10:30