linux-kernel - Re: [PATCH 0/2] memcg: mm_update_next

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Message-ID: <20140419083455.GA17601@amd.pavel.ucw.cz>
Date:	Sat, 19 Apr 2014 10:34:55 +0200
From:	Pavel Machek <pavel@....cz>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Chiang <pchiang@...dia.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Balbir Singh <bsingharora@...il.com>,
	Michal Hocko <mhocko@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	"ccross@...roid.com" <ccross@...roid.com>,
	"lizefan@...wei.com" <lizefan@...wei.com>,
	"tj@...nel.org" <tj@...nel.org>,
	"ebiederm@...ssion.com" <ebiederm@...ssion.com>,
	"guillaume@...infr.org" <guillaume@...infr.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] memcg: mm_update_next_owner() should skip kthreads

Hi!

> > Hmm. I seem to see a bug in this function, it can be fulled by use_mm,
> > but I am not sure this can explain the problem. I'll send a patch.
> 
> Untested, please review. But it really looks "obviously wrong", and note
> that unuse_mm() doesn't do mm_update_next_owner(). (just in case, do not
> confuse it with unuse_mm() in mm/swapfile.c).

Having two functions, one exported, one static with same name -- that
sounds quite evil, right?

mmu_context.c: * unuse_mm
mmu_context.c:void unuse_mm(struct mm_struct *mm)
mmu_context.c:EXPORT_SYMBOL_GPL(unuse_mm);
swapfile.c:static int unuse_mm(struct mm_struct *mm,
swapfile.c:	      		      retval = unuse_mm(start_mm,
entry, page);
swapfile.c:					retval = unuse_mm(mm,
entry, page);
swapfile.c:		 * or while we dropped it in unuse_mm().  The
page might even

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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