From: Michal Hocko <mhocko@suse.cz>
To: David Rientjes <rientjes@google.com>
Cc: Xiubo Li <Li.Xiubo@freescale.com>,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>,
vbabka@suse.cz, mgorman@suse.de, minchan@kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH] mm/compaction: Fix warning of 'flags' may be used uninitialized
Date: Thu, 11 Sep 2014 10:04:55 +0200 [thread overview]
Message-ID: <20140911080455.GA22047@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.02.1409101149500.27173@chino.kir.corp.google.com>
On Wed 10-09-14 11:50:41, David Rientjes wrote:
> On Wed, 10 Sep 2014, Xiubo Li wrote:
>
> > C mm/compaction.o
> > mm/compaction.c: In function isolate_freepages_block:
> > mm/compaction.c:364:37: warning: flags may be used uninitialized in
> > this function [-Wmaybe-uninitialized]
> > && compact_unlock_should_abort(&cc->zone->lock, flags,
> > ^
> > In file included from include/linux/irqflags.h:15:0,
> > from ./arch/arm/include/asm/bitops.h:27,
> > from include/linux/bitops.h:33,
> > from include/linux/kernel.h:10,
> > from include/linux/list.h:8,
> > from include/linux/preempt.h:10,
> > from include/linux/spinlock.h:50,
> > from include/linux/swap.h:4,
> > from mm/compaction.c:10:
> > mm/compaction.c: In function isolate_migratepages_block:
> > ./arch/arm/include/asm/irqflags.h:152:2: warning: flags may be used
> > uninitialized in this function [-Wmaybe-uninitialized]
> > asm volatile(
> > ^
> > mm/compaction.c:576:16: note: flags as declared here
> > unsigned long flags;
> > ^
> >
> > Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
>
> Arnd Bergmann already sent a patch for this to use uninitialized_var()
> privately but it didn't get cc'd to any mailing list, sorry.
Besides that setting flags to 0 is certainly a misleading way to fix
this issue. uninitialized_var is a correct way because the warning is a
false possitive. compact_unlock_should_abort will not touch the flags if
locked is false and this is true only after a lock has been taken and
flags set. (this should be preferably in the patch description).
--
Michal Hocko
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-09-11 8:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-10 6:12 Xiubo Li
2014-09-10 18:50 ` David Rientjes
2014-09-11 8:04 ` Michal Hocko [this message]
2014-09-11 9:27 ` Li.Xiubo
2014-09-11 9:02 ` Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140911080455.GA22047@dhcp22.suse.cz \
--to=mhocko@suse.cz \
--cc=Li.Xiubo@freescale.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=minchan@kernel.org \
--cc=rientjes@google.com \
--cc=vbabka@suse.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox