The patch titled From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> has been added to the -mm tree. Its filename is mm-correctly-synchronize-rss-counters-at-exit-exec.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> Subject: mm: correctly synchronize rss-counters at exit/exec mm->rss_stat counters have per-task delta: task->rss_stat. Before changing task->mm pointer the kernel must flush this delta with sync_mm_rss(). do_exit() already calls sync_mm_rss() to flush the rss-counters before committing the rss statistics into task->signal->maxrss, taskstats, audit and other stuff. Unfortunately the kernel does this before calling mm_release(), which can call put_user() for processing task->clear_child_tid. So at this point we can trigger page-faults and task->rss_stat becomes non-zero again. As a result mm->rss_stat becomes inconsistent and check_mm() will print something like this: | BUG: Bad rss-counter state mm:ffff88020813c380 idx:1 val:-1 | BUG: Bad rss-counter state mm:ffff88020813c380 idx:2 val:1 This patch moves sync_mm_rss() into mm_release(), and moves mm_release() out of do_exit() and calls it earlier. After mm_release() there should be no pagefaults. Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> Reported-by: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/exec.c | 1 - kernel/exit.c | 9 +++++---- kernel/fork.c | 8 ++++++++ 3 files changed, 13 insertions(+), 5 deletions(-) diff -puN fs/exec.c~mm-correctly-synchronize-rss-counters-at-exit-exec fs/exec.c --- a/fs/exec.c~mm-correctly-synchronize-rss-counters-at-exit-exec +++ a/fs/exec.c @@ -823,7 +823,6 @@ static int exec_mmap(struct mm_struct *m /* Notify parent that we're no longer interested in the old VM */ tsk = current; old_mm = current->mm; - sync_mm_rss(old_mm); mm_release(tsk, old_mm); if (old_mm) { diff -puN kernel/exit.c~mm-correctly-synchronize-rss-counters-at-exit-exec kernel/exit.c --- a/kernel/exit.c~mm-correctly-synchronize-rss-counters-at-exit-exec +++ a/kernel/exit.c @@ -423,6 +423,7 @@ void daemonize(const char *name, ...) * user space pages. We don't need them, and if we didn't close them * they would be locked into memory. */ + mm_release(current, current->mm); exit_mm(current); /* * We don't want to get frozen, in case system-wide hibernation @@ -640,7 +641,6 @@ static void exit_mm(struct task_struct * struct mm_struct *mm = tsk->mm; struct core_state *core_state; - mm_release(tsk, mm); if (!mm) return; /* @@ -959,9 +959,10 @@ void do_exit(long code) preempt_count()); acct_update_integrals(tsk); - /* sync mm's RSS info before statistics gathering */ - if (tsk->mm) - sync_mm_rss(tsk->mm); + + /* Release mm and sync mm's RSS info before statistics gathering */ + mm_release(tsk, tsk->mm); + group_dead = atomic_dec_and_test(&tsk->signal->live); if (group_dead) { hrtimer_cancel(&tsk->signal->real_timer); diff -puN kernel/fork.c~mm-correctly-synchronize-rss-counters-at-exit-exec kernel/fork.c --- a/kernel/fork.c~mm-correctly-synchronize-rss-counters-at-exit-exec +++ a/kernel/fork.c @@ -780,6 +780,14 @@ void mm_release(struct task_struct *tsk, } tsk->clear_child_tid = NULL; } + + /* + * Final rss-counter synchronization. After this point must be + * no page-faults into this mm from current context, otherwise + * mm->rss_stat will be inconsistent. + */ + if (mm) + sync_mm_rss(mm); } /* _ Subject: From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> Patches currently in -mm which might be from khlebnikov@xxxxxxxxxx are linux-next.patch mm-correctly-synchronize-rss-counters-at-exit-exec.patch mm-correctly-synchronize-rss-counters-at-exit-exec-fix.patch mm-vmscan-remove-lumpy-reclaim.patch mm-vmscan-remove-reclaim_mode_t.patch mm-fix-page-faults-detection-in-swap-token-logic.patch mm-memcg-scanning_global_lru-means-mem_cgroup_disabled.patch mm-memcg-move-reclaim_stat-into-lruvec.patch mm-push-lru-index-into-shrink_active_list.patch mm-push-lru-index-into-shrink_active_list-fix.patch mm-mark-mm-inline-functions-as-__always_inline.patch mm-remove-lru-type-checks-from-__isolate_lru_page.patch mm-memcg-kill-mem_cgroup_lru_del.patch mm-memcg-use-vm_swappiness-from-target-memory-cgroup.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html