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![]() The per-task oom_adj value is a characteristic of its mm more than the task itself since it's not possible to oom kill any thread that shares the mm. If a task were to be killed while attached to an mm that could not be freed because another thread were set to OOM_DISABLE, it would have needlessly been terminated since there is no potential for future memory freeing. This patch moves oomkilladj (now more appropriately named oom_adj) from struct task_struct to struct mm_struct. This requires task_lock() on a task to check its oom_adj value to protect against exec, but it's already necessary to take the lock when dereferencing the mm to find the total VM size for the badness heuristic. This fixes a livelock if the oom killer chooses a task and another thread sharing the same memory has an oom_adj value of OOM_DISABLE. This occurs because oom_kill_task() repeatedly returns 1 and refuses to kill the chosen task while select_bad_process() will repeatedly choose the same task during the next retry. Taking task_lock() in select_bad_process() to check for OOM_DISABLE and in oom_kill_task() to check for threads sharing the same memory will be removed in the next patch in this series where it will no longer be necessary. Writing to /proc/pid/oom_adj for a kthread will now return -EINVAL since these threads are immune from oom killing already. They simply report an oom_adj value of OOM_DISABLE. Cc: Nick Piggin <npiggin@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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.. | ||
array.c | ||
base.c | ||
cmdline.c | ||
cpuinfo.c | ||
devices.c | ||
generic.c | ||
inode.c | ||
internal.h | ||
interrupts.c | ||
Kconfig | ||
kcore.c | ||
kmsg.c | ||
loadavg.c | ||
Makefile | ||
meminfo.c | ||
mmu.c | ||
nommu.c | ||
page.c | ||
proc_devtree.c | ||
proc_net.c | ||
proc_sysctl.c | ||
proc_tty.c | ||
root.c | ||
stat.c | ||
task_mmu.c | ||
task_nommu.c | ||
uptime.c | ||
version.c | ||
vmcore.c |