From: Hugh Dickins <hughd@google.com>
To: Dave Jones <davej@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: shmem_getpage_gfp VM_BUG_ON triggered. [3.7rc2]
Date: Wed, 24 Oct 2012 21:36:27 -0700 (PDT) [thread overview]
Message-ID: <alpine.LNX.2.00.1210242121410.1697@eggly.anvils> (raw)
In-Reply-To: <20121025023738.GA27001@redhat.com>
On Wed, 24 Oct 2012, Dave Jones wrote:
> Machine under significant load (4gb memory used, swap usage fluctuating)
> triggered this...
>
> WARNING: at mm/shmem.c:1151 shmem_getpage_gfp+0xa5c/0xa70()
> Pid: 29795, comm: trinity-child4 Not tainted 3.7.0-rc2+ #49
> Call Trace:
> [<ffffffff8107100f>] warn_slowpath_common+0x7f/0xc0
> [<ffffffff8107106a>] warn_slowpath_null+0x1a/0x20
> [<ffffffff811903fc>] shmem_getpage_gfp+0xa5c/0xa70
> [<ffffffff8118fc3e>] ? shmem_getpage_gfp+0x29e/0xa70
> [<ffffffff81190e4f>] shmem_fault+0x4f/0xa0
> [<ffffffff8119f391>] __do_fault+0x71/0x5c0
> [<ffffffff810e1ac6>] ? __lock_acquire+0x306/0x1ba0
> [<ffffffff810b6ff9>] ? local_clock+0x89/0xa0
> [<ffffffff811a2767>] handle_pte_fault+0x97/0xae0
> [<ffffffff816d1069>] ? sub_preempt_count+0x79/0xd0
> [<ffffffff8136d68e>] ? delay_tsc+0xae/0x120
> [<ffffffff8136d578>] ? __const_udelay+0x28/0x30
> [<ffffffff811a4a39>] handle_mm_fault+0x289/0x350
> [<ffffffff816d091e>] __do_page_fault+0x18e/0x530
> [<ffffffff810b6ff9>] ? local_clock+0x89/0xa0
> [<ffffffff810b0e51>] ? get_parent_ip+0x11/0x50
> [<ffffffff810b0e51>] ? get_parent_ip+0x11/0x50
> [<ffffffff816d1069>] ? sub_preempt_count+0x79/0xd0
> [<ffffffff8112d389>] ? rcu_user_exit+0xc9/0xf0
> [<ffffffff816d0ceb>] do_page_fault+0x2b/0x50
> [<ffffffff816cd3b8>] page_fault+0x28/0x30
> [<ffffffff8136d259>] ? copy_user_enhanced_fast_string+0x9/0x20
> [<ffffffff8121c181>] ? sys_futimesat+0x41/0xe0
> [<ffffffff8102bf35>] ? syscall_trace_enter+0x25/0x2c0
> [<ffffffff816d5625>] ? tracesys+0x7e/0xe6
> [<ffffffff816d5688>] tracesys+0xe1/0xe6
>
>
>
> 1148 error = shmem_add_to_page_cache(page, mapping, index,
> 1149 gfp, swp_to_radix_entry(swap));
> 1150 /* We already confirmed swap, and make no allocation */
> 1151 VM_BUG_ON(error);
> 1152 }
That's very surprising. Easy enough to handle an error there, but
of course I made it a VM_BUG_ON because it violates my assumptions:
I rather need to understand how this can be, and I've no idea.
Clutching at straws, I expect this is entirely irrelevant, but:
there isn't a warning on line 1151 of mm/shmem.c in 3.7.0-rc2 nor
in current linux.git; rather, there's a VM_BUG_ON on line 1149.
So you've inserted a couple of lines for some reason (more useful
trinity behaviour, perhaps)? And have some config option I'm
unfamiliar with, that mutates a BUG_ON or VM_BUG_ON into a warning?
Hugh
>
>
> total used free shared buffers cached
> Mem: 3885528 2854064 1031464 0 9624 19208
> -/+ buffers/cache: 2825232 1060296
> Swap: 6029308 30656 5998652
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next prev parent reply other threads:[~2012-10-25 4:36 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-25 2:37 Dave Jones
2012-10-25 4:36 ` Hugh Dickins [this message]
2012-10-25 4:50 ` Ni zhan Chen
2012-10-25 6:59 ` Hugh Dickins
2012-10-25 9:53 ` Ni zhan Chen
2012-10-25 10:21 ` Ni zhan Chen
2012-10-25 21:27 ` Hugh Dickins
2012-10-26 1:48 ` Ni zhan Chen
2012-10-25 11:14 ` Dave Jones
2012-10-25 21:28 ` Hugh Dickins
2012-10-25 20:52 ` Johannes Weiner
2012-10-25 21:48 ` Hugh Dickins
2012-10-26 2:15 ` Ni zhan Chen
2012-11-01 19:10 ` Dave Jones
2012-11-01 23:03 ` Hugh Dickins
2012-11-01 23:20 ` Dave Jones
2012-11-01 23:48 ` Hugh Dickins
2012-11-02 1:43 ` Dave Jones
2012-11-02 23:26 ` Hugh Dickins
2012-11-06 1:32 ` [PATCH] tmpfs: fix shmem_getpage_gfp VM_BUG_ON Hugh Dickins
2012-11-06 13:54 ` Dave Jones
2012-11-06 23:48 ` Hugh Dickins
2012-11-07 22:38 ` Dave Jones
2012-11-14 1:36 ` [PATCH] tmpfs: fix shmem_getpage_gfp VM_BUG_ON fix Hugh Dickins
2012-11-14 3:07 ` [PATCH] tmpfs: fix shmem_getpage_gfp VM_BUG_ON Jaegeuk Hanse
2012-11-14 3:50 ` Hugh Dickins
2012-11-14 6:14 ` Dave Jones
2012-11-14 10:06 ` Hugh Dickins
2012-11-15 7:39 ` Jaegeuk Hanse
2012-11-15 19:56 ` Hugh Dickins
2012-11-16 0:40 ` Jaegeuk Hanse
2012-11-16 9:34 ` Jaegeuk Hanse
2012-11-17 4:48 ` Hugh Dickins
2012-11-18 0:57 ` Jaegeuk Hanse
2012-11-18 1:48 ` Jaegeuk Hanse
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