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From: Lorenzo Stoakes <lstoakes@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm <linux-mm@kvack.org>,
	bugzilla-daemon@bugzilla.kernel.org,  vladi@aresgate.net,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>
Subject: Re: [Bug 210075] New: [Thu Nov 5 13:14:27 2020] WARNING: CPU: 4 PID: 133 at mm/page_counter.c:57 page_counter_uncharge+0x34/0x40
Date: Sun, 8 Nov 2020 17:49:27 +0000	[thread overview]
Message-ID: <CAA5enKauk_xoTvq+8iGREsmpmPw6m_eKQg8E42Hc6d6oD4hbzQ@mail.gmail.com> (raw)
In-Reply-To: <20201106211300.23179b5680fd8c83a07a095b@linux-foundation.org>

Looking to jump back into some kernel hacking again so thought I'd
take a quick rusty look.

Pattern matching a bit but I wonder whether f2fe7b09 (mm: memcg/slab:
charge individual slab objects instead of pages) may have had a role
in this bug as it adds an obj_cgroup_uncharge() invocation to
memcg_slab_free_hook() invoked from kmem_cache_free(). sk_prot_free()
also invokes mem_cgroup_sk_free() before kmem_cache_free() so perhaps
an uncharge is getting doubled up here? I traced through
mem_cgroup_sk_free() (which invokes css_put()) but couldn't see where
it would result in an additional uncharge so I may be barking up the
wrong tree here.

I'd be more than happy to have a deeper look at this if vladi has some
code that repro's this + a .config, if that'd be helpful.

Best, Lorenzo


  reply	other threads:[~2020-11-08 17:49 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-210075-27@https.bugzilla.kernel.org/>
2020-11-07  5:13 ` Andrew Morton
2020-11-08 17:49   ` Lorenzo Stoakes [this message]
2020-11-09  8:16   ` Michal Hocko
2020-11-09 17:39     ` Shakeel Butt

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