From: Greg KH <gregkh@linuxfoundation.org>
To: Julius Hemanth Pitti <jpitti@cisco.com>
Cc: akpm@linux-foundation.org, xlpang@linux.alibaba.com,
mhocko@suse.com, vdavydov.dev@gmail.com, ktkhai@virtuozzo.com,
hannes@cmpxchg.org, stable@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, xe-linux-external@cisco.com,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH stable v5.4] mm: memcg: fix memcg reclaim soft lockup
Date: Fri, 25 Sep 2020 12:55:55 +0200 [thread overview]
Message-ID: <20200925105555.GA2525199@kroah.com> (raw)
In-Reply-To: <20200921180508.61905-1-jpitti@cisco.com>
On Mon, Sep 21, 2020 at 11:05:08AM -0700, Julius Hemanth Pitti wrote:
> From: Xunlei Pang <xlpang@linux.alibaba.com>
>
> commit e3336cab2579012b1e72b5265adf98e2d6e244ad upstream
>
> We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg
> doesn't have any reclaimable memory.
>
> It can be easily reproduced as below:
>
> watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204]
> CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12
> Call Trace:
> shrink_lruvec+0x49f/0x640
> shrink_node+0x2a6/0x6f0
> do_try_to_free_pages+0xe9/0x3e0
> try_to_free_mem_cgroup_pages+0xef/0x1f0
> try_charge+0x2c1/0x750
> mem_cgroup_charge+0xd7/0x240
> __add_to_page_cache_locked+0x2fd/0x370
> add_to_page_cache_lru+0x4a/0xc0
> pagecache_get_page+0x10b/0x2f0
> filemap_fault+0x661/0xad0
> ext4_filemap_fault+0x2c/0x40
> __do_fault+0x4d/0xf9
> handle_mm_fault+0x1080/0x1790
>
> It only happens on our 1-vcpu instances, because there's no chance for
> oom reaper to run to reclaim the to-be-killed process.
>
> Add a cond_resched() at the upper shrink_node_memcgs() to solve this
> issue, this will mean that we will get a scheduling point for each memcg
> in the reclaimed hierarchy without any dependency on the reclaimable
> memory in that memcg thus making it more predictable.
>
> [jpitti@cisco.com:
> - backported to v5.4.y
> - Upstream patch applies fix in shrink_node_memcgs(), which
> is not present to v5.4.y. Appled to shrink_node()]
Thanks for this, now queued up here and for 4.19
greg k-h
prev parent reply other threads:[~2020-09-25 10:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 18:05 Julius Hemanth Pitti
2020-09-25 10:55 ` Greg KH [this message]
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