On Thu 27-08-15 00:34:47, Tetsuo Handa wrote: > 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> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > 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 -- Michal Hocko SUSE Labs _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
