From: Nicholas Piggin <npiggin@xxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx: 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@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Vaneet Narang <v.narang@xxxxxxxxxxx> Cc: Maninder Singh <maninder1.s@xxxxxxxxxxx> Cc: Amit Sahrawat <a.sahrawat@xxxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20201029032320.1448441-1-npiggin@xxxxxxxxx Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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; }