Commit 901608d9045146aec6f14a7777ea4b1501c379f0
Committed by
Linus Torvalds
Linus Torvalds
1 parent
67d58ac47d
Exists in
master
and in
4 other branches
mm: introduce get_mm_hiwater_xxx(), fix taskstats->hiwater_xxx accounting
xacct_add_tsk() relies on do_exit()->update_hiwater_xxx() and uses mm->hiwater_xxx directly, this leads to 2 problems: - taskstats_user_cmd() can call fill_pid()->xacct_add_tsk() at any moment before the task exits, so we should check the current values of rss/vm anyway. - do_exit()->update_hiwater_xxx() calls are racy. An exiting thread can be preempted right before mm->hiwater_xxx = new_val, and another thread can use A_LOT of memory and exit in between. When the first thread resumes it can be the last thread in the thread group, in that case we report the wrong hiwater_xxx values which do not take A_LOT into account. Introduce get_mm_hiwater_rss() and get_mm_hiwater_vm() helpers and change xacct_add_tsk() to use them. The first helper will also be used by rusage->ru_maxrss accounting. Kill do_exit()->update_hiwater_xxx() calls. Unless we are going to decrease rss/vm there is no point to update mm->hiwater_xxx, and nobody can look at this mm_struct when exit_mmap() actually unmaps the memory. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Hugh Dickins <hugh@veritas.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Showing 4 changed files with 7 additions and 7 deletions Side-by-side Diff
include/linux/sched.h
| ... | ... | @@ -386,6 +386,9 @@ |
| 386 | 386 | (mm)->hiwater_vm = (mm)->total_vm; \ |
| 387 | 387 | } while (0) |
| 388 | 388 | |
| 389 | +#define get_mm_hiwater_rss(mm) max((mm)->hiwater_rss, get_mm_rss(mm)) | |
| 390 | +#define get_mm_hiwater_vm(mm) max((mm)->hiwater_vm, (mm)->total_vm) | |
| 391 | + | |
| 389 | 392 | extern void set_dumpable(struct mm_struct *mm, int value); |
| 390 | 393 | extern int get_dumpable(struct mm_struct *mm); |
| 391 | 394 |
kernel/exit.c
| ... | ... | @@ -1051,10 +1051,7 @@ |
| 1051 | 1051 | preempt_count()); |
| 1052 | 1052 | |
| 1053 | 1053 | acct_update_integrals(tsk); |
| 1054 | - if (tsk->mm) { | |
| 1055 | - update_hiwater_rss(tsk->mm); | |
| 1056 | - update_hiwater_vm(tsk->mm); | |
| 1057 | - } | |
| 1054 | + | |
| 1058 | 1055 | group_dead = atomic_dec_and_test(&tsk->signal->live); |
| 1059 | 1056 | if (group_dead) { |
| 1060 | 1057 | hrtimer_cancel(&tsk->signal->real_timer); |
kernel/tsacct.c
| ... | ... | @@ -92,8 +92,8 @@ |
| 92 | 92 | mm = get_task_mm(p); |
| 93 | 93 | if (mm) { |
| 94 | 94 | /* adjust to KB unit */ |
| 95 | - stats->hiwater_rss = mm->hiwater_rss * PAGE_SIZE / KB; | |
| 96 | - stats->hiwater_vm = mm->hiwater_vm * PAGE_SIZE / KB; | |
| 95 | + stats->hiwater_rss = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB; | |
| 96 | + stats->hiwater_vm = get_mm_hiwater_vm(mm) * PAGE_SIZE / KB; | |
| 97 | 97 | mmput(mm); |
| 98 | 98 | } |
| 99 | 99 | stats->read_char = p->ioac.rchar; |
mm/mmap.c
| ... | ... | @@ -2102,7 +2102,7 @@ |
| 2102 | 2102 | lru_add_drain(); |
| 2103 | 2103 | flush_cache_mm(mm); |
| 2104 | 2104 | tlb = tlb_gather_mmu(mm, 1); |
| 2105 | - /* Don't update_hiwater_rss(mm) here, do_exit already did */ | |
| 2105 | + /* update_hiwater_rss(mm) here? but nobody should be looking */ | |
| 2106 | 2106 | /* Use -1 here to ensure all VMAs in the mm are unmapped */ |
| 2107 | 2107 | end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); |
| 2108 | 2108 | vm_unacct_memory(nr_accounted); |