The patch titled
Subject: mm/compaction: no stuck in __reset_isolation_pfn()
has been added to the -mm tree. Its filename is
mm-compaction-be-selective-about-what-pageblocks-to-clear-skip-hints-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-be-selective-about-what-pageblocks-to-clear-skip-hints-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-be-selective-about-what-pageblocks-to-clear-skip-hints-fix.patch
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------------------------------------------------------
From: Qian Cai <cai@xxxxxx>
Subject: mm/compaction: no stuck in __reset_isolation_pfn()
c68d77911c23 ("mm, compaction: be selective about what pageblocks to clear
skip hints") introduced an infinite loop if a pfn is invalid, it will loop
again without increasing page counters. It can be reproduced by running
LTP tests on an arm64 server.
# oom01 (swapping)
# hugemmap01
tst_test.c:1096: INFO: Timeout per run is 0h 05m 00s
mem.c:814: INFO: set nr_hugepages to 128
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Test timeouted, sending SIGKILL!
Cannot kill test processes!
Congratulation, likely test hit a kernel bug.
Also, triggers soft lockups.
[ 456.232228] watchdog: BUG: soft lockup - CPU#122 stuck for 22s! [kswapd0:1375]
[ 456.273354] pstate: 80400009 (Nzcv daif +PAN -UAO)
[ 456.278143] pc : pfn_valid+0x54/0xdc
[ 456.281713] lr : __reset_isolation_pfn+0x3a8/0x584
[ 456.369358] Call trace:
[ 456.371798] pfn_valid+0x54/0xdc
[ 456.375019] __reset_isolation_pfn+0x3a8/0x584
[ 456.379455] __reset_isolation_suitable+0x1bc/0x280
[ 456.384325] reset_isolation_suitable+0xb8/0xe0
[ 456.388847] kswapd+0xd08/0x1048
[ 456.392067] kthread+0x2f4/0x30c
[ 456.395289] ret_from_fork+0x10/0x18
Link: http://lkml.kernel.org/r/20190206034732.75687-1-cai@xxxxxx
Fixes: c68d77911c23 ("mm, compaction: be selective about what pageblocks to clear skip hints")
Signed-off-by: Qian Cai <cai@xxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: YueHaibing <yuehaibing@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/compaction.c~mm-compaction-be-selective-about-what-pageblocks-to-clear-skip-hints-fix
+++ a/mm/compaction.c
@@ -282,17 +282,16 @@ __reset_isolation_pfn(struct zone *zone,
end_page = pfn_to_page(pfn);
do {
- if (!pfn_valid_within(pfn))
- continue;
+ if (pfn_valid_within(pfn)) {
+ if (check_source && PageLRU(page)) {
+ clear_pageblock_skip(page);
+ return true;
+ }
- if (check_source && PageLRU(page)) {
- clear_pageblock_skip(page);
- return true;
- }
-
- if (check_target && PageBuddy(page)) {
- clear_pageblock_skip(page);
- return true;
+ if (check_target && PageBuddy(page)) {
+ clear_pageblock_skip(page);
+ return true;
+ }
}
page += (1 << PAGE_ALLOC_COSTLY_ORDER);
_
Patches currently in -mm which might be from cai@xxxxxx are
revert-mm-use-early_pfn_to_nid-in-page_ext_init.patch
page_poison-play-nicely-with-kasan.patch
slab-kmemleak-no-scan-alien-caches.patch
mm-compaction-be-selective-about-what-pageblocks-to-clear-skip-hints-fix.patch
signal-allow-the-null-signal-in-rt_sigqueueinfo.patch
