https://github.com/torvalds/linux
Revision b385d21f27d86426472f6ae92a231095f7de2a8d authored by Hugh Dickins on 24 September 2016, 03:27:04 UTC, committed by Linus Torvalds on 24 September 2016, 18:20:01 UTC
init_tlb_ubc() looked unnecessary to me: tlb_ubc is statically initialized with zeroes in the init_task, and copied from parent to child while it is quiescent in arch_dup_task_struct(); so I went to delete it. But inserted temporary debug WARN_ONs in place of init_tlb_ubc() to check that it was always empty at that point, and found them firing: because memcg reclaim can recurse into global reclaim (when allocating biosets for swapout in my case), and arrive back at the init_tlb_ubc() in shrink_node_memcg(). Resetting tlb_ubc.flush_required at that point is wrong: if the upper level needs a deferred TLB flush, but the lower level turns out not to, we miss a TLB flush. But fortunately, that's the only part of the protocol that does not nest: with the initialization removed, cpumask collects bits from upper and lower levels, and flushes TLB when needed. Fixes: 72b252aed506 ("mm: send one IPI per CPU to TLB flush all entries after unmapping pages") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: stable@vger.kernel.org # 4.3+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Tip revision: b385d21f27d86426472f6ae92a231095f7de2a8d authored by Hugh Dickins on 24 September 2016, 03:27:04 UTC
mm: delete unnecessary and unsafe init_tlb_ubc()
mm: delete unnecessary and unsafe init_tlb_ubc()
Tip revision: b385d21
File | Mode | Size |
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Documentation | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 31 bytes |
.gitignore | -rw-r--r-- | 1.3 KB |
.mailmap | -rw-r--r-- | 7.3 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 95.5 KB |
Kbuild | -rw-r--r-- | 2.8 KB |
Kconfig | -rw-r--r-- | 252 bytes |
MAINTAINERS | -rw-r--r-- | 363.7 KB |
Makefile | -rw-r--r-- | 56.8 KB |
README | -rw-r--r-- | 18.1 KB |
REPORTING-BUGS | -rw-r--r-- | 7.3 KB |
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