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Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED

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From: Rik van Riel
Subject: Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED
Date: Sunday, June 29, 2008 - 8:16 am

On Sun, 29 Jun 2008 17:48:59 +0900
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:


I have been running with a similar patch for a while, and
got my system to OOM :)

However, the patch is correct and the OOM is caused by
a different issue.  When stress-testing with a loopback
device on a tmpfs file, the VM thinks that we succeed
in evicting pages from the loopback device (file LRUs)
and continues scanning those LRUs.

Unfortunately for the VM, the loopback writepage function,
in combination with splice, end up moving the pages to the
anon LRUs, instead of freeing any pages.  

This confuses the balancing code, which thinks the pages
got freed.  As a result, the VM keeps scanning the file
LRUs and will eventually realize it failed to free any
memory.

One of Kosaki-san's recent patches may fix this, though.

-- 
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Messages in current thread:
[PATCH] splitlru: shmem_getpage SetPageSwapBacked sooner, Hugh Dickins, (Sat Jun 28, 5:20 pm)
[PATCH] splitlru: memcg swapbacked pages active, Hugh Dickins, (Sat Jun 28, 5:22 pm)
[PATCH] splitlru: BDI_CAP_SWAP_BACKED, Hugh Dickins, (Sat Jun 28, 5:24 pm)
Re: [PATCH] splitlru: shmem_getpage SetPageSwapBacked sooner, KOSAKI Motohiro, (Sun Jun 29, 1:09 am)
Re: [PATCH] splitlru: memcg swapbacked pages active, KOSAKI Motohiro, (Sun Jun 29, 1:19 am)
Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED, KOSAKI Motohiro, (Sun Jun 29, 1:48 am)
Re: [PATCH] splitlru: memcg swapbacked pages active, Hugh Dickins, (Sun Jun 29, 5:20 am)
Re: [PATCH] splitlru: memcg swapbacked pages active, KOSAKI Motohiro, (Sun Jun 29, 5:58 am)
Re: [PATCH] splitlru: memcg swapbacked pages active, Hugh Dickins, (Sun Jun 29, 6:51 am)
Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED, Rik van Riel, (Sun Jun 29, 8:16 am)
Re: [PATCH] splitlru: memcg swapbacked pages active, KAMEZAWA Hiroyuki, (Sun Jun 29, 7:44 pm)
Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED, KAMEZAWA Hiroyuki, (Sun Jun 29, 7:53 pm)
[RFC][PATCH] memcg: change shmem handler., KAMEZAWA Hiroyuki, (Mon Jun 30, 1:36 am)
Re: [PATCH] splitlru: memcg swapbacked pages active, Hugh Dickins, (Mon Jun 30, 12:19 pm)
Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED, Hugh Dickins, (Mon Jun 30, 12:23 pm)
Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED, Rik van Riel, (Mon Jun 30, 12:49 pm)
Re: [RFC][PATCH] memcg: change shmem handler., Hugh Dickins, (Mon Jun 30, 12:52 pm)
Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED, Hugh Dickins, (Mon Jun 30, 1:55 pm)
Re: [PATCH] splitlru: BDI_CAP_SWAP_BACKED, Rik van Riel, (Mon Jun 30, 2:17 pm)
Re: Re: [RFC][PATCH] memcg: change shmem handler., kamezawa.hiroyu, (Mon Jun 30, 5:56 pm)
Re: Re: Re: [RFC][PATCH] memcg: change shmem handler., kamezawa.hiroyu, (Mon Jun 30, 6:06 pm)
[RFC][PATCH] memcg: shmem swap cache, KAMEZAWA Hiroyuki, (Tue Jul 1, 7:16 pm)
Re: [RFC][PATCH] memcg: change shmem handler., Balbir Singh, (Thu Jul 3, 12:15 am)
Re: [RFC][PATCH] memcg: change shmem handler., KAMEZAWA Hiroyuki, (Thu Jul 3, 12:56 am)