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From: Michal Hocko <mhocko@kernel.org>
To: Hugh Dickins <hughd@google.com>
Cc: lkft-triage@lists.linaro.org, linux-mm <linux-mm@kvack.org>,
	Yafang Shao <laoar.shao@gmail.com>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Cgroups <cgroups@vger.kernel.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Anders Roxell <anders.roxell@linaro.org>,
	Naresh Kamboju <naresh.kamboju@linaro.org>,
	Matthew Wilcox <willy@infradead.org>,
	Linux-Next Mailing List <linux-next@vger.kernel.org>,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-block <linux-block@vger.kernel.org>,
	Jaegeuk Kim <jaegeuk@kernel.org>, Theodore Ts'o <tytso@mit.edu>,
	Chris Down <chris@chrisdown.name>,
	open list <linux-kernel@vger.kernel.org>,
	"Linux F2FS DEV,
	Mailing List" <linux-f2fs-devel@lists.sourceforge.net>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>
Subject: Re: [f2fs-dev] mm: mkfs.ext4 invoked oom-killer on i386 - pagecache_get_page
Date: Thu, 21 May 2020 14:44:44 +0200
Message-ID: <20200521124444.GP6462@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.11.2005210504110.1185@eggly.anvils>

On Thu 21-05-20 05:24:27, Hugh Dickins wrote:
> On Thu, 21 May 2020, Michal Hocko wrote:
> > On Thu 21-05-20 16:11:11, Naresh Kamboju wrote:
> > > On Thu, 21 May 2020 at 15:25, Michal Hocko <mhocko@kernel.org> wrote:
> > > >
> > > > On Wed 20-05-20 20:09:06, Chris Down wrote:
> > > > > Hi Naresh,
> > > > >
> > > > > Naresh Kamboju writes:
> > > > > > As a part of investigation on this issue LKFT teammate Anders Roxell
> > > > > > git bisected the problem and found bad commit(s) which caused this problem.
> > > > > >
> > > > > > The following two patches have been reverted on next-20200519 and retested the
> > > > > > reproducible steps and confirmed the test case mkfs -t ext4 got PASS.
> > > > > > ( invoked oom-killer is gone now)
> > > > > >
> > > > > > Revert "mm, memcg: avoid stale protection values when cgroup is above
> > > > > > protection"
> > > > > >    This reverts commit 23a53e1c02006120f89383270d46cbd040a70bc6.
> > > > > >
> > > > > > Revert "mm, memcg: decouple e{low,min} state mutations from protection
> > > > > > checks"
> > > > > >    This reverts commit 7b88906ab7399b58bb088c28befe50bcce076d82.
> > > > >
> > > > > Thanks Anders and Naresh for tracking this down and reverting.
> > > > >
> > > > > I'll take a look tomorrow. I don't see anything immediately obviously wrong
> > > > > in either of those commits from a (very) cursory glance, but they should
> > > > > only be taking effect if protections are set.
> > > >
> > > > Agreed. If memory.{low,min} is not used then the patch should be
> > > > effectively a nop. Btw. do you see the problem when booting with
> > > > cgroup_disable=memory kernel command line parameter?
> > > 
> > > With extra kernel command line parameters, cgroup_disable=memory
> > > I have noticed a differ problem now.
> > > 
> > > + mkfs -t ext4 /dev/disk/by-id/ata-TOSHIBA_MG04ACA100N_Y8NRK0BPF6XF
> > > mke2fs 1.43.8 (1-Jan-2018)
> > > Creating filesystem with 244190646 4k blocks and 61054976 inodes
> > > Filesystem UUID: 3bb1a285-2cb4-44b4-b6e8-62548f3ac620
> > > Superblock backups stored on blocks:
> > > 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
> > > 4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
> > > 102400000, 214990848
> > > Allocating group tables:    0/7453                           done
> > > Writing inode tables:    0/7453                           done
> > > Creating journal (262144 blocks): [   35.502102] BUG: kernel NULL
> > > pointer dereference, address: 000000c8
> > > [   35.508372] #PF: supervisor read access in kernel mode
> > > [   35.513506] #PF: error_code(0x0000) - not-present page
> > > [   35.518638] *pde = 00000000
> > > [   35.521514] Oops: 0000 [#1] SMP
> > > [   35.524652] CPU: 0 PID: 145 Comm: kswapd0 Not tainted
> > > 5.7.0-rc6-next-20200519+ #1
> > > [   35.532121] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS
> > > 2.2 05/23/2018
> > > [   35.539507] EIP: mem_cgroup_get_nr_swap_pages+0x28/0x60
> > 
> > Could you get faddr2line for this offset?
> 
> No need for that, I can help with the "cgroup_disabled=memory" crash:
> I've been happily running with the fixup below, but haven't got to
> send it in yet (and wouldn't normally be reading mail at this time!)
> because of busy chasing a couple of other bugs (not necessarily mm);
> and maybe the fix would be better with explicit mem_cgroup_disabled()
> test, or maybe that should be where cgroup_memory_noswap is decided -
> up to Johannes.

Thanks Hugh. I can see what is the problem now. I was looking at the
Linus' tree and we have a different code there

	long nr_swap_pages = get_nr_swap_pages();

        if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
                return nr_swap_pages;

which would be impossible to crash so I was really wondering what is
going on here. But there are other changes in the mmotm which I haven't
reviewed yet. Looking at the next tree now it is a fallout from "mm:
memcontrol: prepare swap controller setup for integration".

!memcg check slightly more cryptic than an explicit mem_cgroup_disabled
but I would just leave it to Johannes as well.

> 
> ---
> 
>  mm/memcontrol.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> --- 5.7-rc6-mm1/mm/memcontrol.c	2020-05-20 12:21:56.109693740 -0700
> +++ linux/mm/memcontrol.c	2020-05-20 12:26:15.500478753 -0700
> @@ -6954,7 +6954,8 @@ long mem_cgroup_get_nr_swap_pages(struct
>  {
>  	long nr_swap_pages = get_nr_swap_pages();
>  
> -	if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
> +	if (!memcg || cgroup_memory_noswap ||
> +            !cgroup_subsys_on_dfl(memory_cgrp_subsys))
>  		return nr_swap_pages;
>  	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
>  		nr_swap_pages = min_t(long, nr_swap_pages,

-- 
Michal Hocko
SUSE Labs


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Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-01 12:38 Naresh Kamboju
2020-05-01 20:58 ` Andrew Morton
2020-05-18 14:10   ` Naresh Kamboju
2020-05-19  7:52     ` Michal Hocko
2020-05-19  8:11       ` Arnd Bergmann
2020-05-19  8:45         ` Michal Hocko
2020-05-20 11:56           ` Naresh Kamboju
2020-05-20 17:59             ` Naresh Kamboju
2020-05-20 19:09               ` Chris Down
2020-05-21  9:22                 ` Naresh Kamboju
2020-05-21  9:35                   ` Arnd Bergmann
2020-05-21  9:55                 ` Michal Hocko
2020-05-21 10:41                   ` Naresh Kamboju
2020-05-21 10:58                     ` Michal Hocko
2020-05-21 12:24                       ` Hugh Dickins via Linux-f2fs-devel
2020-05-21 12:44                         ` Michal Hocko [this message]
2020-05-21 19:17                           ` Johannes Weiner
2020-05-21 20:06                             ` Hugh Dickins via Linux-f2fs-devel
2020-05-21 21:58                               ` Johannes Weiner
2020-05-21 23:35                                 ` Hugh Dickins via Linux-f2fs-devel
2020-05-28 14:59                                 ` Michal Hocko
2020-05-21 16:34                   ` Michal Hocko
2020-05-21 19:00                     ` Naresh Kamboju
2020-05-21 20:53                       ` Naresh Kamboju
2020-05-28 15:03                         ` Michal Hocko
2020-05-28 16:17                           ` Naresh Kamboju
2020-05-28 16:41                             ` Chris Down
2020-05-29  1:50                               ` Yafang Shao
2020-05-29  1:56                                 ` Chris Down
2020-05-29  9:49                                   ` Michal Hocko
2020-05-21  2:39               ` Yafang Shao
2020-05-21  8:58                 ` Naresh Kamboju
2020-05-21  9:47                   ` Yafang Shao

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