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Date: Sat, 21 May 2011 23:31:45 +0900
Message-ID: <BANLkTimfPXXcTamkR1kTgOu55iy14ybTpA@mail.gmail.com>
Subject: Re: Kernel falls apart under light memory pressure (i.e. linking vmlinux)
From: Minchan Kim <minchan.kim@gmail.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Lutomirski <luto@mit.edu>, Andrea Arcangeli <aarcange@redhat.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        fengguang.wu@intel.com, andi@firstfloor.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, mgorman@suse.de, hannes@cmpxchg.org,
        riel@redhat.com
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On Sat, May 21, 2011 at 9:04 PM, 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.

Hi KOSAKI,
You're absolutely right.
I missed that so the problem should not happen. :(

-- 
Kind regards,
Minchan Kim
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