[PATCH 5.9 212/255] mm/vmscan: fix NR_ISOLATED_FILE corruption on 64-bit

Greg Kroah-Hartman
2020-11-17T13:44:44Z

From: Nicholas Piggin <npiggin@gmail.com>

commit 2da9f6305f306ffbbb44790675799328fb73119d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/vmscan.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1514,7 +1514,8 @@ unsigned int reclaim_clean_pages_from_li
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
@@ -1524,7 +1525,7 @@ unsigned int reclaim_clean_pages_from_li
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;
}