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ce9ce6659a
kernel_optimize_test/mm
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Sebastian Andrzej Siewior ce9ce6659a mm: memcontrol: bring back the VM_BUG_ON() in mem_cgroup_swapout() 
Clark stumbled over a VM_BUG_ON() in -RT which was then was removed by
Johannes in commit f371763a79 ("mm: memcontrol: fix false-positive
VM_BUG_ON() on -rt").  The comment before that patch was a tiny bit better
than it is now.  While the patch claimed to fix a false-postive on -RT
this was not the case.  None of the -RT folks ACKed it and it was not a
false positive report.  That was a *real* problem.

This patch updates the comment that is improper because it refers to
"disabled preemption" as a consequence of that lock being taken.  A
spin_lock() disables preemption, true, but in this case the code relies on
the fact that the lock _also_ disables interrupts once it is acquired.
And this is the important detail (which was checked the VM_BUG_ON()) which
needs to be pointed out.  This is the hint one needs while looking at the
code.  It was explained by Johannes on the list that the per-CPU variables
are protected by local_irq_save().  The BUG_ON() was helpful.  This code
has been workarounded in -RT in the meantime.  I wouldn't mind running
into more of those if the code in question uses *special* kind of locking
since now there is no verification (in terms of lockdep or BUG_ON()) and
therefore I bring the VM_BUG_ON() check back in.

The two functions after the comment could also have a "local_irq_save()"
dance around them in order to serialize access to the per-CPU variables.
This has been avoided because the interrupts should be off.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Clark Williams <williams@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
..
kasan x86/kasan, mm: Introduce generic kasan_populate_zero_shadow() 2015-08-22 14:54:55 +02:00
backing-dev.c writeback: don't drain bdi_writeback_congested on bdi destruction 2015-07-02 08:46:00 -06:00
balloon_compaction.c mm/balloon_compaction: fix deflation when compaction is disabled 2014-10-29 16:33:15 -07:00
bootmem.c mm: page_alloc: pass PFN to __free_pages_bootmem 2015-06-30 19:44:55 -07:00
cleancache.c cleancache: remove limit on the number of cleancache enabled filesystems 2015-04-14 16:49:03 -07:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
cma.c mm/memblock: add extra "flags" to memblock to allow selection of memory based on attribute 2015-06-24 17:49:44 -07:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
compaction.c mm/compaction.c: fix "suitable_migration_target() unused" warning 2015-04-15 16:35:20 -07:00
debug-pagealloc.c mm/debug-pagealloc: make debug-pagealloc boottime configurable 2014-12-13 12:42:48 -08:00
debug.c tracing: Rename ftrace_event.h to trace_events.h 2015-05-13 14:05:12 -04:00
dmapool.c mm/dmapool.c: fixed a brace coding style issue 2014-10-09 22:26:00 -04:00
early_ioremap.c
fadvise.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
failslab.c
filemap.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-07-04 19:36:06 -07:00
frontswap.c frontswap: allow multiple backends 2015-06-24 17:49:45 -07:00
gup.c mm: use READ_ONCE() for non-scalar types 2015-04-15 16:35:18 -07:00
highmem.c
huge_memory.c userfaultfd: propagate the full address in THP faults 2015-09-04 16:54:41 -07:00
hugetlb_cgroup.c mm: page_counter: pull "-1" handling out of page_counter_memparse() 2015-02-11 17:06:02 -08:00
hugetlb.c mm/hugetlb: remove unused arch hook prepare/release_hugepage 2015-06-25 17:00:35 -07:00
hwpoison-inject.c mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling 2015-06-24 17:49:42 -07:00
init-mm.c
internal.h mm: defer flush of writable TLB entries 2015-09-04 16:54:41 -07:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
Kconfig mm/Kconfig: NEED_BOUNCE_POOL: clean-up condition 2015-07-23 20:59:41 +02:00
Kconfig.debug mm/debug_pagealloc: remove obsolete Kconfig options 2015-01-08 15:10:52 -08:00
kmemcheck.c mm/slab_common: move kmem_cache definition to internal header 2014-10-09 22:25:50 -04:00
kmemleak-test.c
kmemleak.c mm: kmemleak_alloc_percpu() should follow the gfp from per_alloc() 2015-06-24 17:49:46 -07:00
ksm.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
list_lru.c memcg: reparent list_lrus and free kmemcg_id on css offline 2015-02-12 18:54:10 -08:00
maccess.c lib: move strncpy_from_unsafe() into mm/maccess.c 2015-08-31 12:36:10 -07:00
madvise.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
Makefile userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation 2015-09-04 16:54:41 -07:00
memblock.c mm/memblock: WARN_ON when nid differs from overlap region 2015-09-04 16:54:41 -07:00
memcontrol.c mm: memcontrol: bring back the VM_BUG_ON() in mem_cgroup_swapout() 2015-09-04 16:54:41 -07:00
memory_hotplug.c memory-hotplug: add hot-added memory ranges to memblock before allocate node_data for a node. 2015-09-04 16:54:41 -07:00
memory-failure.c mm/hwpoison: fix panic due to split huge zero page 2015-08-14 15:56:32 -07:00
memory.c userfaultfd: call handle_userfault() for userfaultfd_missing() faults 2015-09-04 16:54:41 -07:00
mempolicy.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mempool.c mm/mempool.c: kasan: poison mempool elements 2015-04-15 16:35:20 -07:00
memtest.c mm/memblock: add extra "flags" to memblock to allow selection of memory based on attribute 2015-06-24 17:49:44 -07:00
migrate.c mm/memory-failure: set PageHWPoison before migrate_pages() 2015-08-07 04:39:42 +03:00
mincore.c mincore: apply page table walker on do_mincore() 2015-02-11 17:06:06 -08:00
mlock.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mm_init.c mm: meminit: remove mminit_verify_page_links 2015-06-30 19:44:56 -07:00
mmap.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mmu_context.c
mmu_notifier.c mmu_notifier: add the callback for mmu_notifier_invalidate_range() 2014-11-13 13:46:09 +11:00
mmzone.c mm: microoptimize zonelist operations 2015-02-11 17:06:02 -08:00
mprotect.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mremap.c mm: new arch_remap() hook 2015-06-24 17:49:41 -07:00
msync.c mm: remove rest usage of VM_NONLINEAR and pte_file() 2015-02-10 14:30:31 -08:00
nobootmem.c mm: page_alloc: pass PFN to __free_pages_bootmem 2015-06-30 19:44:55 -07:00
nommu.c Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2015-09-01 18:46:42 -07:00
oom_kill.c mm/oom_kill.c: print points as unsigned int 2015-06-24 17:49:44 -07:00
page_alloc.c mm: make page pfmemalloc check more robust 2015-08-21 14:30:10 -07:00
page_counter.c mm: page_counter: pull "-1" handling out of page_counter_memparse() 2015-02-11 17:06:02 -08:00
page_ext.c mm/page_owner: keep track of page owners 2014-12-13 12:42:48 -08:00
page_io.c fs: use helper bio_add_page() instead of open coding on bi_io_vec 2015-08-13 12:32:00 -06:00
page_isolation.c CMA: page_isolation: check buddy before accessing it 2015-05-14 17:55:51 -07:00
page_owner.c mm/page_owner: set correct gfp_mask on page_owner 2015-07-17 16:39:54 -07:00
page-writeback.c writeback: fix initial dirty limit 2015-08-07 04:39:42 +03:00
pagewalk.c mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed to callers 2015-03-25 16:20:30 -07:00
percpu-km.c
percpu-vm.c
percpu.c percpu: clean up of schunk->map[] assignment in pcpu_setup_first_chunk 2015-07-21 11:31:00 -04:00
pgtable-generic.c mm: clarify that the function operates on hugepage pte 2015-06-24 17:49:44 -07:00
process_vm_access.c process_vm_access: switch to {compat_,}import_iovec() 2015-04-11 22:27:12 -04:00
quicklist.c
readahead.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
rmap.c mm: defer flush of writable TLB entries 2015-09-04 16:54:41 -07:00
shmem.c ipc: use private shmem or hugetlbfs inodes for shm segments. 2015-08-07 04:39:41 +03:00
slab_common.c slab: infrastructure for bulk object allocation and freeing 2015-09-04 16:54:41 -07:00
slab.c slab: infrastructure for bulk object allocation and freeing 2015-09-04 16:54:41 -07:00
slab.h mm/slab.h: fix argument order in cache_from_obj's error message 2015-09-04 16:54:41 -07:00
slob.c slab: infrastructure for bulk object allocation and freeing 2015-09-04 16:54:41 -07:00
slub.c mm/slub: don't wait for high-order page allocation 2015-09-04 16:54:41 -07:00
sparse-vmemmap.c
sparse.c
swap_cgroup.c mm: page_cgroup: rename file to mm/swap_cgroup.c 2014-12-10 17:41:09 -08:00
swap_state.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
swap.c mm: drop bogus VM_BUG_ON_PAGE assert in put_page() codepath 2015-06-24 17:49:42 -07:00
swapfile.c vfs: add seq_file_path() helper 2015-06-23 18:01:07 -04:00
truncate.c memcg: add per cgroup dirty page accounting 2015-06-02 08:33:33 -06:00
userfaultfd.c userfaultfd: avoid mmap_sem read recursion in mcopy_atomic 2015-09-04 16:54:41 -07:00
util.c mm: uninline and cleanup page-mapping related helpers 2015-04-15 16:35:19 -07:00
vmacache.c mm,vmacache: count number of system-wide flushes 2014-12-13 12:42:48 -08:00
vmalloc.c mm/vmalloc: get rid of dirty bitmap inside vmap_block structure 2015-04-15 16:35:18 -07:00
vmpressure.c mm/vmpressure.c: fix race in vmpressure_work_fn() 2014-12-02 17:32:07 -08:00
vmscan.c mm: defer flush of writable TLB entries 2015-09-04 16:54:41 -07:00
vmstat.c vmstat: Reduce time interval to stat update on idle cpu 2015-02-11 17:06:07 -08:00
workingset.c list_lru: add helpers to isolate items 2015-02-12 18:54:10 -08:00
zbud.c zpool: remove zpool_evict() 2015-06-25 17:00:37 -07:00
zpool.c zpool: remove zpool_evict() 2015-06-25 17:00:37 -07:00
zsmalloc.c zpool: remove zpool_evict() 2015-06-25 17:00:37 -07:00
zswap.c zswap: runtime enable/disable 2015-06-25 17:00:37 -07:00