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Linus Torvalds c56af023a5 mm: don't pointlessly use BUG_ON() for sanity check 
commit 50f5aa8a9b upstream.

BUG_ON() is a big hammer, and should be used _only_ if there is some
major corruption that you cannot possibly recover from, making it
imperative that the current process (and possibly the whole machine) be
terminated with extreme prejudice.

The trivial sanity check in the vmacache code is *not* such a fatal
error.  Recovering from it is absolutely trivial, and using BUG_ON()
just makes it harder to debug for no actual advantage.

To make matters worse, the placement of the BUG_ON() (only if the range
check matched) actually makes it harder to hit the sanity check to begin
with, so _if_ there is a bug (and we just got a report from Srivatsa
Bhat that this can indeed trigger), it is harder to debug not just
because the machine is possibly dead, but because we don't have better
coverage.

BUG_ON() must *die*.  Maybe we should add a checkpatch warning for it,
because it is simply just about the worst thing you can ever do if you
hit some "this cannot happen" situation.

Reported-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2014-10-09 12:21:29 -07:00
..
Kconfig parisc,metag: Do not hardcode maximum userspace stack size 2014-07-17 16:21:03 -07:00
Kconfig.debug mm: more intensive memory corruption debugging 2012-01-10 16:30:42 -08:00
Makefile mm: per-thread vma caching 2014-10-09 12:21:29 -07:00
backing-dev.c bdi: avoid oops on device removal 2014-04-26 17:19:05 -07:00
balloon_compaction.c mm: print more details for bad_page() 2014-01-23 16:36:50 -08:00
bootmem.c mm/bootmem.c: remove unused local `map' 2013-11-13 12:09:09 +09:00
bounce.c block: Convert bio_for_each_segment() to bvec_iter 2013-11-23 22:33:49 -08:00
cleancache.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
compaction.c mm, compaction: ignore pageblock skip when manually invoking compaction 2014-10-09 12:21:28 -07:00
debug-pagealloc.c mm, x86: Remove debug_pagealloc_enabled 2011-12-06 09:24:07 +01:00
dmapool.c dmapool: make DMAPOOL_DEBUG detect corruption of free marker 2012-12-11 17:22:24 -08:00
fadvise.c teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long 2013-03-03 22:46:22 -05:00
failslab.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
filemap.c mm/filemap.c: avoid always dirtying mapping->flags on O_DIRECT 2014-10-09 12:21:29 -07:00
filemap_xip.c seqcount: Add lockdep functionality to seqcount/seqlock structures 2013-11-06 12:40:26 +01:00
fremap.c mm: fix bad rss-counter if remap_file_pages raced migration 2014-03-19 16:21:49 -07:00
frontswap.c swap: change swap_list_head to plist, add swap_avail_head 2014-10-09 12:21:28 -07:00
highmem.c Some nice cleanups, and even a patch my wife did as a "live" demo for 2012-12-20 08:37:05 -08:00
huge_memory.c mm: numa: Do not mark PTEs pte_numa when splitting huge pages 2014-10-09 12:21:27 -07:00
hugetlb.c mm: optimize put_mems_allowed() usage 2014-10-09 12:21:28 -07:00
hugetlb_cgroup.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
hwpoison-inject.c mm/hwpoison: add '#' to hwpoison_inject 2014-01-21 16:19:48 -08:00
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h mm: page_alloc: spill to remote nodes before waking kswapd 2014-05-06 07:59:35 -07:00
interval_tree.c mm: add CONFIG_DEBUG_VM_RB build option 2012-10-09 16:22:42 +09:00
kmemcheck.c kmemcheck: Fix build errors due to missing slab.h 2010-03-30 22:02:32 +09:00
kmemleak-test.c kmemleak: remove memset by using kzalloc 2011-01-27 18:31:51 +00:00
kmemleak.c mm: kmemleak: avoid false negatives on vmalloc'ed objects 2013-11-13 12:09:07 +09:00
ksm.c mm: close PageTail race 2014-03-04 07:55:47 -08:00
list_lru.c mm: list_lru: fix almost infinite loop causing effective livelock 2013-10-30 12:57:46 -07:00
maccess.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
madvise.c mm/hwpoison: fix traversal of hugetlbfs pages to avoid printk flood 2013-09-30 14:31:02 -07:00
memblock.c memblock, memhotplug: fix wrong type in memblock_find_in_range_node(). 2014-10-05 14:52:17 -07:00
memcontrol.c memcg: oom_notify use-after-free fix 2014-08-07 14:52:37 -07:00
memory-failure.c mm/memory-failure.c: support use of a dedicated thread to handle SIGBUS(BUS_MCEERR_AO) 2014-06-30 20:11:53 -07:00
memory.c mm: softdirty: keep bit when zapping file pte 2014-10-05 14:52:21 -07:00
memory_hotplug.c mm/memory_hotplug.c: move register_memory_resource out of the lock_memory_hotplug 2014-01-23 16:36:52 -08:00
mempolicy.c mm: optimize put_mems_allowed() usage 2014-10-09 12:21:28 -07:00
mempool.c mm/mempool.c: convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...) 2013-09-11 15:58:14 -07:00
migrate.c mm: migrate: Close race between migration completion and mprotect 2014-10-09 12:21:26 -07:00
mincore.c mm: do_mincore() cleanup 2014-01-23 16:36:52 -08:00
mlock.c mm: try_to_unmap_cluster() should lock_page() before mlocking 2014-05-06 07:59:35 -07:00
mm_init.c mm: bring back /sys/kernel/mm 2014-01-27 21:02:39 -08:00
mmap.c mm: per-thread vma caching 2014-10-09 12:21:29 -07:00
mmu_context.c mm: remove old aio use_mm() comment 2013-05-07 18:38:27 -07:00
mmu_notifier.c mm: audit/fix non-modular users of module_init in core code 2014-01-23 16:36:52 -08:00
mmzone.c mm: numa: Change page last {nid,pid} into {cpu,pid} 2013-10-09 14:47:45 +02:00
mprotect.c mm: Use ptep/pmdp_set_numa() for updating _PAGE_NUMA bit 2014-02-17 11:19:36 +11:00
mremap.c mm, thp: close race between mremap() and split_huge_page() 2014-06-07 10:28:10 -07:00
msync.c sanitize vfs_fsync calling conventions 2010-05-21 18:31:21 -04:00
nobootmem.c mm/nobootmem: free_all_bootmem again 2014-01-23 16:36:52 -08:00
nommu.c mm: per-thread vma caching 2014-10-09 12:21:29 -07:00
oom_kill.c mm, oom: base root bonus on current usage 2014-01-30 16:56:56 -08:00
page-writeback.c mm/page-writeback.c: fix divide by zero in bdi_dirty_limits() 2014-08-07 14:52:37 -07:00
page_alloc.c mm: optimize put_mems_allowed() usage 2014-10-09 12:21:28 -07:00
page_cgroup.c Merge branch 'akpm' (incoming from Andrew) 2014-01-21 19:05:45 -08:00
page_io.c Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block 2014-01-30 11:19:05 -08:00
page_isolation.c mm: memory-hotplug: enable memory hotplug to handle hugepage 2013-09-11 15:57:48 -07:00
pagewalk.c mm/pagewalk.c: fix walk_page_range() access of wrong PTEs 2013-10-30 14:27:03 -07:00
percpu-km.c percpu: clear memory allocated with the km allocator 2010-10-02 10:28:42 +03:00
percpu-vm.c percpu: perform tlb flush after pcpu_map_pages() failure 2014-10-05 14:52:20 -07:00
percpu.c percpu: free percpu allocation info for uniprocessor system 2014-10-05 14:52:20 -07:00
pgtable-generic.c mm: fix TLB flush race between migration, and change_protection_range 2013-12-18 19:04:51 -08:00
process_vm_access.c Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys 2013-03-12 11:05:45 -07:00
quicklist.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
readahead.c mm/readahead.c: fix readahead failure for memoryless NUMA nodes and limit readahead pages 2014-10-09 12:21:28 -07:00
rmap.c mm: fix sleeping function warning from __put_anon_vma 2014-06-30 20:11:53 -07:00
shmem.c shmem: fix nlink for rename overwrite directory 2014-10-05 14:52:17 -07:00
slab.c mm: optimize put_mems_allowed() usage 2014-10-09 12:21:28 -07:00
slab.h memcg, slab: RCU protect memcg_params for root caches 2014-01-23 16:36:51 -08:00
slab_common.c slab_common: fix the check for duplicate slab names 2014-07-31 12:52:55 -07:00
slob.c mm/sl[aou]b: Move kmallocXXX functions to common code 2013-09-04 20:51:33 +03:00
slub.c mm: optimize put_mems_allowed() usage 2014-10-09 12:21:28 -07:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
swap.c mm: close PageTail race 2014-03-04 07:55:47 -08:00
swap_state.c swap: add a simple detector for inappropriate swapin readahead 2014-02-06 13:48:51 -08:00
swapfile.c swap: change swap_list_head to plist, add swap_avail_head 2014-10-09 12:21:28 -07:00
truncate.c truncate: drop 'oldsize' truncate_pagecache() parameter 2013-09-12 15:38:02 -07:00
util.c vm_is_stack: use for_each_thread() rather then buggy while_each_thread() 2014-09-05 16:34:18 -07:00
vmacache.c mm: don't pointlessly use BUG_ON() for sanity check 2014-10-09 12:21:29 -07:00
vmalloc.c Revert "mm/vmalloc: interchage the implementation of vmalloc_to_{pfn,page}" 2014-01-27 21:02:39 -08:00
vmpressure.c arm, pm, vmpressure: add missing slab.h includes 2014-02-03 13:24:01 -05:00
vmscan.c vmscan: reclaim_clean_pages_from_list() must use mod_zone_page_state() 2014-10-09 12:21:29 -07:00
vmstat.c mm, x86: Account for TLB flushes only when debugging 2014-01-25 09:10:41 +01:00
zbud.c mm/zbud: fix some trivial typos in comments 2013-09-11 15:57:35 -07:00
zsmalloc.c zsmalloc: add copyright 2014-01-30 16:56:55 -08:00
zswap.c mm/zswap.c: change params from hidden to ro 2014-01-23 16:36:50 -08:00