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From: Andrew Morton <akpm@linux-foundation.org>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>,
	ngupta@vflare.org, "linux-mm@kvack.org" <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: zram: sleeping vunmap_pmd_range called from atomic zram_make_request
Date: Wed, 26 Mar 2014 14:21:11 -0700	[thread overview]
Message-ID: <20140326142111.fee2e7afa1d455451c8cec89@linux-foundation.org> (raw)
In-Reply-To: <53275359.7000802@oracle.com>

On Mon, 17 Mar 2014 15:56:09 -0400 Sasha Levin <sasha.levin@oracle.com> wrote:

> Hi all,
> 
> While fuzzing with trinity inside a KVM tools guest running the latest -next kernel
> I've stumbled on the following spew:
> 
> [  827.272181] BUG: sleeping function called from invalid context at mm/vmalloc.c:74
> [  827.273204] in_atomic(): 1, irqs_disabled(): 0, pid: 4213, name: kswapd14
> [  827.274080] 1 lock held by kswapd14/4213:
> [  827.274587]  #0:  (&zram->init_lock){++++.-}, at: zram_make_request (drivers/block/zram/zram_drv.c:765)
> [  827.275923] Preemption disabled zram_bvec_write (drivers/block/zram/zram_drv.c:500)
> [  827.276910]
> [  827.277104] CPU: 30 PID: 4213 Comm: kswapd14 Tainted: G        W     3.14.0-rc6-next-20140317-sasha-00012-ge933921-dirty #226
> [  827.278467]  ffff880229700000 ffff8802296fd388 ffffffff8449ebb3 0000000000000001
> [  827.279610]  0000000000000000 ffff8802296fd3b8 ffffffff81176cec ffff8802296fd3c8
> [  827.281258]
> [  827.281549]  ffff88032b40a000 ffffc900077fa000 ffffc900077f8000 ffff8802296fd428
> [  827.282911] Call Trace:
> [  827.283318]  dump_stack (lib/dump_stack.c:52)
> [  827.284013]  __might_sleep (kernel/sched/core.c:7016)
> [  827.284797]  vunmap_pmd_range (mm/vmalloc.c:74)

I expect this was caused by
mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges.patch
and its folloup
mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges-fix.patch.

The second patch proved that the first patch can't add cond_resched()
in the vunmap_page_range() path.  I dropped both patches on March 18th.


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      parent reply	other threads:[~2014-03-26 21:21 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-17 19:56 zram: sleeping vunmap_pmd_range called from atomic zram_make_request Sasha Levin
2014-03-19  1:36 ` Minchan Kim
2014-03-26 21:21 ` Andrew Morton [this message]

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