Commit 2da9f630 authored Nov 13, 2020 by Nicholas Piggin Committed by Linus Torvalds Nov 14, 2020

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 730ec8c0
("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: 730ec8c0 ("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>

parent d20bdd57

mm/vmscan.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

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