https://github.com/torvalds/linux
Revision 30acbabae38793c9c9acace4de5b1c1889570768 authored by Hugh Dickins on 27 June 2007, 21:09:53 UTC, committed by Linus Torvalds on 28 June 2007, 18:34:53 UTC
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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Tip revision: 30acbabae38793c9c9acace4de5b1c1889570768 authored by Hugh Dickins on 27 June 2007, 21:09:53 UTC
mm: kill validate_anon_vma to avoid mapcount BUG
mm: kill validate_anon_vma to avoid mapcount BUG
Tip revision: 30acbab
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init | ||
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kernel | ||
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.gitignore | -rw-r--r-- | 572 bytes |
.mailmap | -rw-r--r-- | 3.6 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 89.3 KB |
Kbuild | -rw-r--r-- | 1.5 KB |
MAINTAINERS | -rw-r--r-- | 87.8 KB |
Makefile | -rw-r--r-- | 49.2 KB |
README | -rw-r--r-- | 16.5 KB |
REPORTING-BUGS | -rw-r--r-- | 3.0 KB |
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