From: Mark Tinguely <tinguely@sgi.com>
To: Jan Kara <jack@suse.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: Fix xfs_attr_leafblock definition
Date: Thu, 13 Aug 2015 08:17:17 -0500 [thread overview]
Message-ID: <55CC98DD.6060700@sgi.com> (raw)
In-Reply-To: <1439458000-28395-1-git-send-email-jack@suse.com>
On 08/13/15 04:26, Jan Kara wrote:
> struct xfs_attr_leafblock contains 'entries' array which is declared
> with size 1 altough it can in fact contain much more entries. Since this
> array is followed by further struct members, gcc (at least in version
> 4.8.3) thinks that the array has the fixed size of 1 element and thus
> may optimize away all accesses beyond the end of array resulting in
> non-working code. This problem was only observed with userspace code in
> xfsprogs, however it's better to be safe in kernel as well and have
> matching kernel and xfsprogs definitions.
>
> Signed-off-by: Jan Kara<jack@suse.com>
> ---
I hit this bug in SLES12 and RHEL7 XFS kernel code. It is the gcc 4.8's
new loop optimization routine. A person can bypass it with the option:
-fno-aggressive-loop-optimizations
but this fixes the source of the problem.
Acked-by: Mark Tinguely <tinguely@sgi.com>
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next prev parent reply other threads:[~2015-08-13 13:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-13 9:26 [PATCH] xfs: Fix xfs_attr_leafblock definition Jan Kara
2015-08-13 13:17 ` Mark Tinguely [this message]
2015-08-17 23:57 ` Dave Chinner
2015-08-14 3:02 ` Eric Sandeen
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