linux-kernel - Re: linux-next: build warnings after merge of the akpm-current tree

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Thu, 29 Aug 2013 12:42:08 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Maxim Patlasov <mpatlasov@...allels.com>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	<linux-next@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: build warnings after merge of the akpm-current tree

On Thu, 29 Aug 2013 15:24:46 +0400 Maxim Patlasov <mpatlasov@...allels.com> wrote:

> Hi Stephen,
> 
> 08/29/2013 01:47 PM, Stephen Rothwell __________:
> > Hi Andrew,
> >
> > After merging the akpm tree, today's linux-next build (sparc64 defconfig
> > and others) produced these warnings:
> >
> > mm/page-writeback.c: In function 'balance_dirty_pages_ratelimited':
> > mm/page-writeback.c:1450:13: warning: 'bdi_thresh' may be used uninitialized in this function [-Wuninitialized]
> > mm/page-writeback.c:1372:16: note: 'bdi_thresh' was declared here
> > mm/page-writeback.c:1226:16: warning: 'bdi_dirty' may be used uninitialized in this function [-Wuninitialized]
> > mm/page-writeback.c:1369:16: note: 'bdi_dirty' was declared here
> >
> > Possibly introduced by commit 34c547af1e23 ("mm/page-writeback.c: add
> > strictlimit feature"), but I am not sure anything can be done about them.
> >
> 
> This looks as gcc glitch. So far as I didn't observe the warnings, the 
> version of gcc does matter. May be moving the definitions of the two 
> variables into for(;;){...} would help. Could you please give it a try?

Shuffling the definitions around won't help.  To fix this we'll need to
add more code and I hate adding runtime overhead to address
compile-time issues.  So...

--- a/mm/page-writeback.c~a
+++ a/mm/page-writeback.c
@@ -1366,10 +1366,8 @@ static void balance_dirty_pages(struct a
 {
 	unsigned long nr_reclaimable;	/* = file_dirty + unstable_nfs */
 	unsigned long nr_dirty;  /* = file_dirty + writeback + unstable_nfs */
-	unsigned long bdi_dirty;
 	unsigned long background_thresh;
 	unsigned long dirty_thresh;
-	unsigned long bdi_thresh;
 	long period;
 	long pause;
 	long max_pause;
@@ -1385,8 +1383,10 @@ static void balance_dirty_pages(struct a
 
 	for (;;) {
 		unsigned long now = jiffies;
-		unsigned long dirty;
+		unsigned long uninitialized_var(bdi_thresh);
 		unsigned long thresh;
+		unsigned long uninitialized_var(bdi_dirty);
+		unsigned long dirty;
 		unsigned long bg_thresh;
 
 		/*
_


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/