# Be quiet and do not echo the cmd
Q = @
# Try to use bash as shell for make
SHELL := $(shell if [ -x /bin/bash ]; then echo /bin/bash; else echo /bin/sh; fi)
# Compiler related stuff
LDQ = $(Q)echo -e " LD\t$@" && $(CCACHE) $(CC)
CCNQ = $(CCACHE) $(CC)
CCQ = $(Q)echo -e " CC\t$<" && $(CCNQ)
# sparse related
C =
ifeq ($(C), 1)
CHECK = $(Q)echo -e " CHECK\t$<" && sparse
else
CHECK = @true
endif
# Flex/bison related
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# Installation related
INST = echo -e " INST\t$(1)" && install -d $(2) && \
install --mode=644 -DC $(1) $(2)/$(shell basename $(1))
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ifeq ("$(origin PREFIX)", "$(filter $(origin PREFIX), file command line)")
INSTX = echo -e " INST\t$(1)" && install -d $(2) && \
install -C $(1) $(2)/$(shell basename $(1))
else
INSTX = echo -e " INST\t$(1)" && install -C $(1) $(2)/$(shell basename $(1))
endif
MKDIR = echo -e " MKDIR\t$(1)" && mkdir -p $(1)
RM = echo -e " RM\t$(1)" && rm -rf $(1)
RMDIR = echo -e " RM\t$(1)" && rmdir --ignore-fail-on-non-empty $(1) 2> /dev/null || true
GZIP = gzip -9 -c
# Git related
GIT_LAST_TAG = git describe --abbrev=0 v$(VERSION_SHORT)^
GIT_ARCHIVE = git archive --prefix=netsniff-ng-$(VERSION_SHORT)/ v$(VERSION_SHORT) | \
$(1) > ../netsniff-ng-$(VERSION_SHORT).tar.$(2)
GIT_TAG = git tag -a v$(VERSION_SHORT) -s -m "$(VERSION_SHORT) release"
GIT_LOG = git shortlog -n $(shell $(GIT_LAST_TAG))..HEAD
GIT_REM = git ls-files -o | xargs rm -rf
GIT_PEOPLE = git log --no-merges $(shell $(GIT_LAST_TAG))..HEAD | grep Author: | cut -d: -f2 | \
cut -d\< -f1 | sort | uniq -c | sort -nr
GIT_VERSION = git describe --always
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GPG_SIGN = gpg -a --output ../netsniff-ng-$(VERSION_SHORT).tar.$(1).sign --detach-sig \
../netsniff-ng-$(VERSION_SHORT).tar.$(1)
remove&id=5b398e416e880159fe55eefd93c6588fa072cd66'>treecommitdiff
mm,ksm: fix endless looping in allocating memory when ksm enable
I hit the following hung task when runing a OOM LTP test case with 4.1
kernel.
Call trace:
[<ffffffc000086a88>] __switch_to+0x74/0x8c
[<ffffffc000a1bae0>] __schedule+0x23c/0x7bc
[<ffffffc000a1c09c>] schedule+0x3c/0x94
[<ffffffc000a1eb84>] rwsem_down_write_failed+0x214/0x350
[<ffffffc000a1e32c>] down_write+0x64/0x80
[<ffffffc00021f794>] __ksm_exit+0x90/0x19c
[<ffffffc0000be650>] mmput+0x118/0x11c
[<ffffffc0000c3ec4>] do_exit+0x2dc/0xa74
[<ffffffc0000c46f8>] do_group_exit+0x4c/0xe4
[<ffffffc0000d0f34>] get_signal+0x444/0x5e0
[<ffffffc000089fcc>] do_signal+0x1d8/0x450
[<ffffffc00008a35c>] do_notify_resume+0x70/0x78
The oom victim cannot terminate because it needs to take mmap_sem for
write while the lock is held by ksmd for read which loops in the page
allocator
ksm_do_scan
scan_get_next_rmap_item
down_read
get_next_rmap_item
alloc_rmap_item #ksmd will loop permanently.
There is no way forward because the oom victim cannot release any memory
in 4.1 based kernel. Since 4.6 we have the oom reaper which would solve
this problem because it would release the memory asynchronously.
Nevertheless we can relax alloc_rmap_item requirements and use
__GFP_NORETRY because the allocation failure is acceptable as ksm_do_scan
would just retry later after the lock got dropped.
Such a patch would be also easy to backport to older stable kernels which
do not have oom_reaper.
While we are at it add GFP_NOWARN so the admin doesn't have to be alarmed
by the allocation failure.
Link: http://lkml.kernel.org/r/1474165570-44398-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Suggested-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>