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From: Hugh Dickins <hughd@google.com>
To: Dave Jones <davej@redhat.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: shmem_getpage_gfp VM_BUG_ON triggered. [3.7rc2]
Date: Thu, 1 Nov 2012 16:48:41 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LNX.2.00.1211011627120.19567@eggly.anvils> (raw)
In-Reply-To: <20121101232030.GA25519@redhat.com>

On Thu, 1 Nov 2012, Dave Jones wrote:
> On Thu, Nov 01, 2012 at 04:03:40PM -0700, Hugh Dickins wrote:
>  > 
>  > Except... earlier in the thread you explained how you hacked
>  > #define VM_BUG_ON(cond) WARN_ON(cond)
>  > to get this to come out as a warning instead of a bug,
>  > and now it looks as if "a user" has here done the same.
>  > 
>  > Which is very much a user's right, of course; but does
>  > make me wonder whether that user might actually be davej ;)
> 
> indirectly. I made the same change in the Fedora kernel a while ago
> to test a hypothesis that we weren't getting any VM_BUG_ON reports.

Fedora turns on CONFIG_DEBUG_VM?

All mm developers should thank you for the wider testing exposure;
but I'm not so sure that Fedora users should thank you for turning
it on - really it's for mm developers to wrap around !assertions or
more expensive checks (e.g. checking calls) in their development.

Or did I read a few months ago that some change had been made to
such definitions, and VM_BUG_ON(contents) are evaluated even when
the config option is off?  I do hope I'm mistaken on that.

Hugh

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  reply	other threads:[~2012-11-01 23:48 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
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 [this message]
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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