30acbabae3
validate_anon_vma gave a useful check on the integrity of the anon_vma list when Andrea was developing obj rmap; but it was not enabled in SLES9 itself, nor in mainline, until Nick changed commented-out RMAP_DEBUG to configurable CONFIG_DEBUG_VM in 2.6.17. Now Petr Vandrovec reports that its BUG_ON(mapcount > 100000) can easily crash a CONFIG_DEBUG_VM=y system. That limit was just an arbitrary number to protect against an infinite loop. We could raise it to something enormous (depending on sizeof struct vma and size of memory?); but I rather think validate_anon_vma has outlived its usefulness, and is better just removed - which gives a magnificent performance boost to anything like Petr's test program ;) Of course, a very long anon_vma list is bad news for preemption latency, and I believe there has been one recent report of such: let's not forget that, but validate_anon_vma only makes it worse not better. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Petr Vandrovec <petr@vmware.com> Acked-by: Nick Piggin <npiggin@suse.de> Cc: Andrea Arcangeli <andrea@suse.de> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| allocpercpu.c | ||
| backing-dev.c | ||
| bootmem.c | ||
| bounce.c | ||
| fadvise.c | ||
| filemap_xip.c | ||
| filemap.c | ||
| filemap.h | ||
| fremap.c | ||
| highmem.c | ||
| hugetlb.c | ||
| internal.h | ||
| Kconfig | ||
| madvise.c | ||
| Makefile | ||
| memory_hotplug.c | ||
| memory.c | ||
| mempolicy.c | ||
| mempool.c | ||
| migrate.c | ||
| mincore.c | ||
| mlock.c | ||
| mmap.c | ||
| mmzone.c | ||
| mprotect.c | ||
| mremap.c | ||
| msync.c | ||
| nommu.c | ||
| oom_kill.c | ||
| page_alloc.c | ||
| page_io.c | ||
| page-writeback.c | ||
| pdflush.c | ||
| prio_tree.c | ||
| quicklist.c | ||
| readahead.c | ||
| rmap.c | ||
| shmem_acl.c | ||
| shmem.c | ||
| slab.c | ||
| slob.c | ||
| slub.c | ||
| sparse.c | ||
| swap_state.c | ||
| swap.c | ||
| swapfile.c | ||
| thrash.c | ||
| tiny-shmem.c | ||
| truncate.c | ||
| util.c | ||
| vmalloc.c | ||
| vmscan.c | ||
| vmstat.c | ||