From mboxrd@z Thu Jan  1 00:00:00 1970
From: Chris Down <chris-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org>
Subject: Re: mm: mkfs.ext4 invoked oom-killer on i386 - pagecache_get_page
Date: Fri, 29 May 2020 02:56:44 +0100
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To: Yafang Shao <laoar.shao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Naresh Kamboju <naresh.kamboju-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Anders Roxell <anders.roxell-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, "Linux F2FS DEV, Mailing List" <linux-f2fs-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>, linux-ext4 <linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-block <linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, open list <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Linux-Next Mailing List <linux-next-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-mm <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>, Andreas Dilger <adilger.kernel-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>, Jaegeuk Kim <jaegeuk-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>, Chao Yu <chao-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Andrea Arcangeli <aarcange-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Chao Yu <yuchao0-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>, lkft-

Yafang Shao writes:
>Look at this patch[1] carefully you will find that it introduces the
>same issue that I tried to fix in another patch [2]. Even more sad is
>these two patches are in the same patchset. Although this issue isn't
>related with the issue found by Naresh, we have to ask ourselves why
>we always make the same mistake ?
>One possible answer is that we always forget the lifecyle of
>memory.emin before we read it. memory.emin doesn't have the same
>lifecycle with the memcg, while it really has the same lifecyle with
>the reclaimer. IOW, once a reclaimer begins the protetion value should
>be set to 0, and after we traversal the memcg tree we calculate a
>protection value for this reclaimer, finnaly it disapears after the
>reclaimer stops. That is why I highly suggest to add an new protection
>member in scan_control before.

I agree with you that the e{min,low} lifecycle is confusing for everyone -- the 
only thing I've not seen confirmation of is any confirmed correlation with the 
i386 oom killer issue. If you've validated that, I'd like to see the data :-)