On Thu, Jul 29, 2021 at 09:36:44AM +0100, Mel Gorman wrote:

On Thu, Jul 15, 2021 at 04:35:35AM +0100, Matthew Wilcox (Oracle) wrote:

quoted

These are the folio equivalents of relock_page_lruvec_irq() and
folio_lruvec_relock_irqsave().  Also convert page_matches_lruvec()
to folio_matches_lruvec().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

When build testing what you had in your for-next branch, I got a new
warning for powerpc defconfig

 In file included from ./include/linux/mmzone.h:8,
                  from ./include/linux/gfp.h:6,
                  from ./include/linux/mm.h:10,
                  from mm/swap.c:17:
 mm/swap.c: In function 'release_pages':
 ./include/linux/spinlock.h:290:3: warning: 'flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
   290 |   _raw_spin_unlock_irqrestore(lock, flags); \
       |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~
 mm/swap.c:906:16: note: 'flags' was declared here
   906 |  unsigned long flags;
       |                ^~~~~

I'm fairly sure it's a false positive and the compiler just cannot figure
out that flags are only accessed when lruvec is !NULL and once lruvec is
!NULL, flags are valid

Yes, I read it over carefully and I can't see a way in which this
can happen.  Weird that this change made the compiler unable to figure
that out.  Pushed out a new for-next with your patch included.  Thanks!