Reposting updated version as it turned out that we can call do_send_sig_info() with task_lock held. ;-) ( http://marc.info/?l=linux-mm&m=144059948628905&w=2 ) Tetsuo Handa wrote: > Should selected_tasksize be added to rem even when TIF_MEMDIE was not set? Commit e1099a69a624 "android, lmk: avoid setting TIF_MEMDIE if process has already exited" changed not to add selected_tasksize to rem. But I noticed that rem is initialized to 0 and there is only one addition (i.e. rem += selected_tasksize means rem = selected_tasksize) since commit 7dc19d5affd7 "drivers: convert shrinkers to new count/scan API". I don't know what values we should return, but this patch restores pre commit e1099a69a624 because omitting a call to mark_oom_victim() due to race will not prevent from reclaiming memory because we already sent SIGKILL. ------------------------------------------------------------ >From b7075abd3a1e903e88f1755c68adc017d2125b0d Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Date: Thu, 27 Aug 2015 00:13:57 +0900 Subject: [PATCH 2/2] android, lmk: Send SIGKILL before setting TIF_MEMDIE. It was observed that setting TIF_MEMDIE before sending SIGKILL at oom_kill_process() allows memory reserves to be depleted by allocations which are not needed for terminating the OOM victim. This patch reverts commit 6bc2b856bb7c ("staging: android: lowmemorykiller: set TIF_MEMDIE before send kill sig"), for oom_kill_process() was updated to send SIGKILL before setting TIF_MEMDIE. Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> --- drivers/staging/android/lowmemorykiller.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c index d5d25e4..af604cf 100644 --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -156,26 +156,21 @@ next: } if (selected) { task_lock(selected); - if (!selected->mm) { - /* Already exited, cannot do mark_tsk_oom_victim() */ - task_unlock(selected); - goto out; - } + lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n", + selected->pid, selected->comm, + selected_oom_score_adj, selected_tasksize); + send_sig(SIGKILL, selected, 0); /* * FIXME: lowmemorykiller shouldn't abuse global OOM killer * infrastructure. There is no real reason why the selected * task should have access to the memory reserves. */ - mark_oom_victim(selected); - lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n", - selected->pid, selected->comm, - selected_oom_score_adj, selected_tasksize); + if (selected->mm) + mark_oom_victim(selected); task_unlock(selected); lowmem_deathpending_timeout = jiffies + HZ; - send_sig(SIGKILL, selected, 0); rem += selected_tasksize; } -out: lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n", sc->nr_to_scan, sc->gfp_mask, rem); rcu_read_unlock(); -- 1.8.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>