The patch titled
Subject: mm, compaction: move high_pfn to the for loop scope
has been added to the -mm tree. Its filename is
mm-compaction-move-high_pfn-to-the-for-loop-scope.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-move-high_pfn-to-the-for-loop-scope.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-move-high_pfn-to-the-for-loop-scope.patch
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------------------------------------------------------
From: Rokudo Yan <wu-yan@xxxxxxx>
Subject: mm, compaction: move high_pfn to the for loop scope
In fast_isolate_freepages, high_pfn will be used if a prefered one(PFN >=
low_fn) not found. But the high_pfn is not reset before searching an free
area, so when it was used as freepage, it may from another free area
searched before. And move_freelist_head(freelist, freepage) will have
unexpected behavior(eg. corrupt the MOVABLE freelist)
Unable to handle kernel paging request at virtual address dead000000000200
Mem abort info:
ESR = 0x96000044
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000044
CM = 0, WnR = 1
[dead000000000200] address between user and kernel address ranges
-000|list_cut_before(inline)
-000|move_freelist_head(inline)
-000|fast_isolate_freepages(inline)
-000|isolate_freepages(inline)
-000|compaction_alloc(?, ?)
-001|unmap_and_move(inline)
-001|migrate_pages([NSD:0xFFFFFF80088CBBD0] from = 0xFFFFFF80088CBD88, [NSD:0xFFFFFF80088CBBC8] get_new_p
-002|__read_once_size(inline)
-002|static_key_count(inline)
-002|static_key_false(inline)
-002|trace_mm_compaction_migratepages(inline)
-002|compact_zone(?, [NSD:0xFFFFFF80088CBCB0] capc = 0x0)
-003|kcompactd_do_work(inline)
-003|kcompactd([X19] p = 0xFFFFFF93227FBC40)
-004|kthread([X20] _create = 0xFFFFFFE1AFB26380)
-005|ret_from_fork(asm)
---|end of frame
The issue was reported on an smart phone product with 6GB ram and 3GB zram
as swap device.
This patch fixes the issue by reset high_pfn before searching each free
area, which ensure freepage and freelist match when call
move_freelist_head in fast_isolate_freepages().
Link: http://lkml.kernel.org/r/20190118175136.31341-12-mgorman@xxxxxxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20210112094720.1238444-1-wu-yan@xxxxxxx
Fixes: 5a811889de10f1eb ("mm, compaction: use free lists to quickly locate a migration target")
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/compaction.c~mm-compaction-move-high_pfn-to-the-for-loop-scope
+++ a/mm/compaction.c
@@ -1342,7 +1342,7 @@ fast_isolate_freepages(struct compact_co
{
unsigned int limit = min(1U, freelist_scan_limit(cc) >> 1);
unsigned int nr_scanned = 0;
- unsigned long low_pfn, min_pfn, high_pfn = 0, highest = 0;
+ unsigned long low_pfn, min_pfn, highest = 0;
unsigned long nr_isolated = 0;
unsigned long distance;
struct page *page = NULL;
@@ -1387,6 +1387,7 @@ fast_isolate_freepages(struct compact_co
struct page *freepage;
unsigned long flags;
unsigned int order_scanned = 0;
+ unsigned long high_pfn = 0;
if (!area->nr_free)
continue;
_
Patches currently in -mm which might be from wu-yan@xxxxxxx are
mm-compaction-move-high_pfn-to-the-for-loop-scope.patch
