linux-kernel - [PATCH 5.9 212/255] mm/vmscan: fix NR_ISOLATED

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Date:   Tue, 17 Nov 2020 14:05:52 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nicholas Piggin <npiggin@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vaneet Narang <v.narang@...sung.com>,
        Maninder Singh <maninder1.s@...sung.com>,
        Amit Sahrawat <a.sahrawat@...sung.com>,
        Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.9 212/255] mm/vmscan: fix NR_ISOLATED_FILE corruption on 64-bit

From: Nicholas Piggin <npiggin@...il.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@...ux-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@...il.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Acked-by: Michal Hocko <mhocko@...e.com>
Cc: Vaneet Narang <v.narang@...sung.com>
Cc: Maninder Singh <maninder1.s@...sung.com>
Cc: Amit Sahrawat <a.sahrawat@...sung.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: <stable@...r.kernel.org>
Link: https://lkml.kernel.org/r/20201029032320.1448441-1-npiggin@gmail.com
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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;
 }