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@xxxxxxxxxxxxx> > > 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@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>