Messages in this thread Patch in this message | | | Date | Tue, 29 Sep 2015 16:07:27 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 2/2] mm: fix declarations of nr, delta and nr_pagecache_reclaimable |
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On Sun, 27 Sep 2015 21:04:25 +0000 Alexandru Moise <00moses.alexander00@gmail.com> wrote:
> The nr variable is meant to be returned by a function which is > declared as returning "unsigned long", so declare nr as such. > > Lower down we should also declare delta and nr_pagecache_reclaimable > as being unsigned longs because they're used to store the values > returned by zone_page_state() and zone_unmapped_file_pages() which > also happen to return unsigned integers.
I rewrote the changelog rather a lot:
Subject: mm/vmscan.c: fix types of some locals
In zone_reclaimable_pages(), `nr' is returned by a function which is declared as returning "unsigned long", so declare it such. Negative values are meaningless here.
In zone_pagecache_reclaimable() we should also declare `delta' and `nr_pagecache_reclaimable' as being unsigned longs because they're used to store the values returned by zone_page_state() and zone_unmapped_file_pages() which also happen to return unsigned integers.
> --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -194,7 +194,7 @@ static bool sane_reclaim(struct scan_control *sc) > > static unsigned long zone_reclaimable_pages(struct zone *zone) > { > - int nr; > + unsigned long nr; > > nr = zone_page_state(zone, NR_ACTIVE_FILE) + > zone_page_state(zone, NR_INACTIVE_FILE);
OK.
> @@ -3698,8 +3698,8 @@ static inline unsigned long zone_unmapped_file_pages(struct zone *zone) > /* Work out how many page cache pages we can reclaim in this reclaim_mode */ > static long zone_pagecache_reclaimable(struct zone *zone) > { > - long nr_pagecache_reclaimable; > - long delta = 0; > + unsigned long nr_pagecache_reclaimable; > + unsigned long delta = 0; > > /* > * If RECLAIM_UNMAP is set, then all file pages are considered
Also OK, because zone_pagecache_reclaimable() takes care to avoid returning any negative values.
In fact I believe we should also do this:
--- a/mm/vmscan.c~mm-fix-declarations-of-nr-delta-and-nr_pagecache_reclaimable-fix +++ a/mm/vmscan.c @@ -3693,7 +3693,7 @@ static inline unsigned long zone_unmappe } /* Work out how many page cache pages we can reclaim in this reclaim_mode */ -static long zone_pagecache_reclaimable(struct zone *zone) +static unsigned long zone_pagecache_reclaimable(struct zone *zone) { unsigned long nr_pagecache_reclaimable; unsigned long delta = 0; _
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