Revision 4837fe37adff1d159904f0c013471b1ecbcb455e authored by Michal Hocko on 14 December 2017, 23:33:15 UTC, committed by Linus Torvalds on 15 December 2017, 00:00:49 UTC
David Rientjes has reported the following memory corruption while the oom reaper tries to unmap the victims address space BUG: Bad page map in process oom_reaper pte:6353826300000000 pmd:00000000 addr:00007f50cab1d000 vm_flags:08100073 anon_vma:ffff9eea335603f0 mapping: (null) index:7f50cab1d file: (null) fault: (null) mmap: (null) readpage: (null) CPU: 2 PID: 1001 Comm: oom_reaper Call Trace: unmap_page_range+0x1068/0x1130 __oom_reap_task_mm+0xd5/0x16b oom_reaper+0xff/0x14c kthread+0xc1/0xe0 Tetsuo Handa has noticed that the synchronization inside exit_mmap is insufficient. We only synchronize with the oom reaper if tsk_is_oom_victim which is not true if the final __mmput is called from a different context than the oom victim exit path. This can trivially happen from context of any task which has grabbed mm reference (e.g. to read /proc/<pid>/ file which requires mm etc.). The race would look like this oom_reaper oom_victim task mmget_not_zero do_exit mmput __oom_reap_task_mm mmput __mmput exit_mmap remove_vma unmap_page_range Fix this issue by providing a new mm_is_oom_victim() helper which operates on the mm struct rather than a task. Any context which operates on a remote mm struct should use this helper in place of tsk_is_oom_victim. The flag is set in mark_oom_victim and never cleared so it is stable in the exit_mmap path. Debugged by Tetsuo Handa. Link: http://lkml.kernel.org/r/20171210095130.17110-1-mhocko@kernel.org Fixes: 212925802454 ("mm: oom: let oom_reap_task and exit_mmap run concurrently") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: David Rientjes <rientjes@google.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Andrea Argangeli <andrea@kernel.org> Cc: <stable@vger.kernel.org> [4.14] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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install.sh
#!/bin/sh
#
# This file is subject to the terms and conditions of the GNU General Public
# License. See the file "COPYING" in the main directory of this archive
# for more details.
#
# Copyright (C) 1995 by Linus Torvalds
#
# Adapted from code in arch/i386/boot/Makefile by H. Peter Anvin
#
# "make install" script for m68k architecture
#
# Arguments:
# $1 - kernel version
# $2 - kernel image file
# $3 - kernel map file
# $4 - default install path (blank if root directory)
#
verify () {
if [ ! -f "$1" ]; then
echo "" 1>&2
echo " *** Missing file: $1" 1>&2
echo ' *** You need to run "make" before "make install".' 1>&2
echo "" 1>&2
exit 1
fi
}
# Make sure the files actually exist
verify "$2"
verify "$3"
# User may have a custom install script
if [ -x ~/bin/${INSTALLKERNEL} ]; then exec ~/bin/${INSTALLKERNEL} "$@"; fi
if [ -x /sbin/${INSTALLKERNEL} ]; then exec /sbin/${INSTALLKERNEL} "$@"; fi
# Default install - same as make zlilo
if [ -f $4/vmlinuz ]; then
mv $4/vmlinuz $4/vmlinuz.old
fi
if [ -f $4/System.map ]; then
mv $4/System.map $4/System.old
fi
cat $2 > $4/vmlinuz
cp $3 $4/System.map
sync
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