mm/vmscan: fix NR_ISOLATED_FILE corruption on 64-bit

Previously the negated unsigned long would be cast back to signed long
which would have the correct negative value.  After commit 730ec8c01a2b
("mm/vmscan.c: change prototype for shrink_page_list"), the large
unsigned int converts to a large positive signed long.

Symptoms include CMA allocations hanging forever holding the cma_mutex
due to alloc_contig_range->...->isolate_migratepages_block waiting
forever in "while (unlikely(too_many_isolated(pgdat)))".

[akpm@linux-foundation.org: fix -stat.nr_lazyfree_fail as well, per Michal]

Fixes: 730ec8c01a2b ("mm/vmscan.c: change prototype for shrink_page_list")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vaneet Narang <v.narang@samsung.com>
Cc: Maninder Singh <maninder1.s@samsung.com>
Cc: Amit Sahrawat <a.sahrawat@samsung.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201029032320.1448441-1-npiggin@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1b8f0e059767715deea0ba16125584ab4aa3ff20..7b4e31eac2cff1bfdb80fe9468df0db23e29336d 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1516,7 +1516,8 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
        nr_reclaimed = shrink_page_list(&clean_pages, zone->zone_pgdat, &sc,
                        TTU_IGNORE_ACCESS, &stat, true);
        list_splice(&clean_pages, page_list);
-       mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -nr_reclaimed);
+       mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE,
+                           -(long)nr_reclaimed);
        /*
         * Since lazyfree pages are isolated from file LRU from the beginning,
         * they will rotate back to anonymous LRU in the end if it failed to
@@ -1526,7 +1527,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
        mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON,
                            stat.nr_lazyfree_fail);
        mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE,
-                           -stat.nr_lazyfree_fail);
+                           -(long)stat.nr_lazyfree_fail);
        return nr_reclaimed;
 }