lkml.org 
[lkml]   [2011]   [May]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    SubjectRe: Kernel falls apart under light memory pressure (i.e. linking vmlinux)
    From
    Hi Andrew.

    On Sat, May 21, 2011 at 10:34 PM, Andrew Lutomirski <luto@mit.edu> wrote:
    > On Sat, May 21, 2011 at 8:04 AM, KOSAKI Motohiro
    > <kosaki.motohiro@jp.fujitsu.com> wrote:
    >>> diff --git a/mm/vmscan.c b/mm/vmscan.c
    >>> index 3f44b81..d1dabc9 100644
    >>> @@ -1426,8 +1437,13 @@ shrink_inactive_list(unsigned long nr_to_scan,
    >>> struct zone *zone,
    >>>
    >>>        /* Check if we should syncronously wait for writeback */
    >>>        if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
    >>> +               unsigned long nr_active, old_nr_scanned;
    >>>                set_reclaim_mode(priority, sc, true);
    >>> +               nr_active = clear_active_flags(&page_list, NULL);
    >>> +               count_vm_events(PGDEACTIVATE, nr_active);
    >>> +               old_nr_scanned = sc->nr_scanned;
    >>>                nr_reclaimed += shrink_page_list(&page_list, zone, sc);
    >>> +               sc->nr_scanned = old_nr_scanned;
    >>>        }
    >>>
    >>>        local_irq_disable();
    >>>
    >>> I just tested 2.6.38.6 with the attached patch.  It survived dirty_ram
    >>> and test_mempressure without any problems other than slowness, but
    >>> when I hit ctrl-c to stop test_mempressure, I got the attached oom.
    >>
    >> Minchan,
    >>
    >> I'm confused now.
    >> If pages got SetPageActive(), should_reclaim_stall() should never return true.
    >> Can you please explain which bad scenario was happen?
    >>
    >> -----------------------------------------------------------------------------------------------------
    >> static void reset_reclaim_mode(struct scan_control *sc)
    >> {
    >>        sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
    >> }
    >>
    >> shrink_page_list()
    >> {
    >>  (snip)
    >>  activate_locked:
    >>                SetPageActive(page);
    >>                pgactivate++;
    >>                unlock_page(page);
    >>                reset_reclaim_mode(sc);                  /// here
    >>                list_add(&page->lru, &ret_pages);
    >>        }
    >> -----------------------------------------------------------------------------------------------------
    >>
    >>
    >> -----------------------------------------------------------------------------------------------------
    >> bool should_reclaim_stall()
    >> {
    >>  (snip)
    >>
    >>        /* Only stall on lumpy reclaim */
    >>        if (sc->reclaim_mode & RECLAIM_MODE_SINGLE)   /// and here
    >>                return false;
    >> -----------------------------------------------------------------------------------------------------
    >>
    >
    > I did some tracing and the oops happens from the second call to
    > shrink_page_list after should_reclaim_stall returns true and it hits
    > the same pages in the same order that the earlier call just finished
    > calling SetPageActive on.  I have *not* confirmed that the two calls
    > happened from the same call to shrink_inactive_list, but something's
    > certainly wrong in there.
    >
    > This is very easy to reproduce on my laptop.

    I would like to confirm this problem.
    Could you show the diff of 2.6.38.6 with current your 2.6.38.6 + alpha?
    (ie, I would like to know that what patches you add up on vanilla
    2.6.38.6 to reproduce this problem)
    I believe you added my crap below patch. Right?

    diff --git a/mm/vmscan.c b/mm/vmscan.c
    index 292582c..69d317e 100644
    --- a/mm/vmscan.c
    +++ b/mm/vmscan.c
    @@ -311,7 +311,8 @@ static void set_reclaim_mode(int priority, struct
    scan_control *sc,
    */
    if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
    sc->reclaim_mode |= syncmode;
    - else if (sc->order && priority < DEF_PRIORITY - 2)
    + else if ((sc->order && priority < DEF_PRIORITY - 2) ||
    + prioiry <= DEF_PRIORITY / 3)
    sc->reclaim_mode |= syncmode;
    else
    sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
    @@ -1349,10 +1350,6 @@ static inline bool
    should_reclaim_stall(unsigned long nr_taken,
    if (current_is_kswapd())
    return false;

    - /* Only stall on lumpy reclaim */
    - if (sc->reclaim_mode & RECLAIM_MODE_SINGLE)
    - return false;
    -
    /* If we have relaimed everything on the isolated list, no stall */
    if (nr_freed == nr_taken)
    return false;

    --
    Kind regards,
    Minchan Kim
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2011-05-21 16:47    [W:0.033 / U:31.668 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site