The patch titled
Subject: mm: page-isolation: skip isolated pageblock in start_isolate_page_range()
has been added to the -mm mm-unstable branch. Its filename is
mm-page-isolation-skip-isolated-pageblock-in-start_isolate_page_range.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page-isolation-skip-isolated-pageblock-in-start_isolate_page_range.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Zi Yan <ziy@xxxxxxxxxx>
Subject: mm: page-isolation: skip isolated pageblock in start_isolate_page_range()
Date: Thu, 26 May 2022 19:15:30 -0400
start_isolate_page_range() first isolates the first and the last
pageblocks in the range and ensure pages across range boundaries are split
during isolation. But it missed the case when the range is <= a pageblock
and the first and the last pageblocks are the same one, so the second
isolate_single_pageblock() will always fail. To fix it, skip the
pageblock isolation in second isolate_single_pageblock().
Link: https://lkml.kernel.org/r/20220526231531.2404977-1-zi.yan@xxxxxxxx
Fixes: 88ee134320b8 ("mm: fix a potential infinite loop in start_isolate_page_range()")
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mm/ac65adc0-a7e4-cdfe-a0d8-757195b86293@xxxxxxxxxxx/
Reported-by: Michael Walle <michael@xxxxxxxx>
Tested-by: Michael Walle <michael@xxxxxxxx>
Link: https://lore.kernel.org/linux-mm/8ca048ca8b547e0dd1c95387ee05c23d@xxxxxxxx/
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Doug Berger <opendmb@xxxxxxxxx>
Cc: Eric Ren <renzhengeek@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Qian Cai <quic_qiancai@xxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_isolation.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
--- a/mm/page_isolation.c~mm-page-isolation-skip-isolated-pageblock-in-start_isolate_page_range
+++ a/mm/page_isolation.c
@@ -300,7 +300,7 @@ __first_valid_page(unsigned long pfn, un
* the in-use page then splitting the free page.
*/
static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
- gfp_t gfp_flags, bool isolate_before)
+ gfp_t gfp_flags, bool isolate_before, bool skip_isolation)
{
unsigned char saved_mt;
unsigned long start_pfn;
@@ -327,11 +327,16 @@ static int isolate_single_pageblock(unsi
zone->zone_start_pfn);
saved_mt = get_pageblock_migratetype(pfn_to_page(isolate_pageblock));
- ret = set_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt, flags,
- isolate_pageblock, isolate_pageblock + pageblock_nr_pages);
- if (ret)
- return ret;
+ if (skip_isolation)
+ VM_BUG_ON(!is_migrate_isolate(saved_mt));
+ else {
+ ret = set_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt, flags,
+ isolate_pageblock, isolate_pageblock + pageblock_nr_pages);
+
+ if (ret)
+ return ret;
+ }
/*
* Bail out early when the to-be-isolated pageblock does not form
@@ -463,7 +468,8 @@ static int isolate_single_pageblock(unsi
return 0;
failed:
/* restore the original migratetype */
- unset_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt);
+ if (!skip_isolation)
+ unset_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt);
return -EBUSY;
}
@@ -522,14 +528,18 @@ int start_isolate_page_range(unsigned lo
unsigned long isolate_start = ALIGN_DOWN(start_pfn, pageblock_nr_pages);
unsigned long isolate_end = ALIGN(end_pfn, pageblock_nr_pages);
int ret;
+ bool skip_isolation = false;
/* isolate [isolate_start, isolate_start + pageblock_nr_pages) pageblock */
- ret = isolate_single_pageblock(isolate_start, flags, gfp_flags, false);
+ ret = isolate_single_pageblock(isolate_start, flags, gfp_flags, false, skip_isolation);
if (ret)
return ret;
+ if (isolate_start == isolate_end - pageblock_nr_pages)
+ skip_isolation = true;
+
/* isolate [isolate_end - pageblock_nr_pages, isolate_end) pageblock */
- ret = isolate_single_pageblock(isolate_end, flags, gfp_flags, true);
+ ret = isolate_single_pageblock(isolate_end, flags, gfp_flags, true, skip_isolation);
if (ret) {
unset_migratetype_isolate(pfn_to_page(isolate_start), migratetype);
return ret;
_
Patches currently in -mm which might be from ziy@xxxxxxxxxx are
mm-page-isolation-skip-isolated-pageblock-in-start_isolate_page_range.patch
mm-split-free-page-with-properly-free-memory-accounting-and-without-race.patch
