* [merged] mm-gup-check-every-subpage-of-a-compound-page-during-isolation.patch removed from -mm tree
@ 2021-05-08 22:50 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2021-05-08 22:50 UTC (permalink / raw)
To: dan.j.williams, david, iamjoonsoo.kim, ira.weiny, jgg, jgg,
jhubbard, jmorris, mgorman, mhocko, mhocko, mike.kravetz, mingo,
mm-commits, osalvador, pasha.tatashin, peterz, rientjes, rostedt,
sashal, tyhicks, vbabka, willy
The patch titled
Subject: mm/gup: check every subpage of a compound page during isolation
has been removed from the -mm tree. Its filename was
mm-gup-check-every-subpage-of-a-compound-page-during-isolation.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Pavel Tatashin <pasha.tatashin@soleen.com>
Subject: mm/gup: check every subpage of a compound page during isolation
When pages are isolated in check_and_migrate_movable_pages() we skip
compound number of pages at a time. However, as Jason noted, it is not
necessary correct that pages[i] corresponds to the pages that we skipped.
This is because it is possible that the addresses in this range had
split_huge_pmd()/split_huge_pud(), and these functions do not update the
compound page metadata.
The problem can be reproduced if something like this occurs:
1. User faulted huge pages.
2. split_huge_pmd() was called for some reason
3. User has unmapped some sub-pages in the range
4. User tries to longterm pin the addresses.
The resulting pages[i] might end-up having pages which are not compound
size page aligned.
Link: https://lkml.kernel.org/r/20210215161349.246722-3-pasha.tatashin@soleen.com
Fixes: aa712399c1e8 ("mm/gup: speed up check_and_migrate_cma_pages() on huge page")
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reported-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/gup.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
--- a/mm/gup.c~mm-gup-check-every-subpage-of-a-compound-page-during-isolation
+++ a/mm/gup.c
@@ -1609,26 +1609,23 @@ static long check_and_migrate_cma_pages(
unsigned int gup_flags)
{
unsigned long i;
- unsigned long step;
bool drain_allow = true;
bool migrate_allow = true;
LIST_HEAD(cma_page_list);
long ret = nr_pages;
+ struct page *prev_head, *head;
struct migration_target_control mtc = {
.nid = NUMA_NO_NODE,
.gfp_mask = GFP_USER | __GFP_NOWARN,
};
check_again:
- for (i = 0; i < nr_pages;) {
-
- struct page *head = compound_head(pages[i]);
-
- /*
- * gup may start from a tail page. Advance step by the left
- * part.
- */
- step = compound_nr(head) - (pages[i] - head);
+ prev_head = NULL;
+ for (i = 0; i < nr_pages; i++) {
+ head = compound_head(pages[i]);
+ if (head == prev_head)
+ continue;
+ prev_head = head;
/*
* If we get a page from the CMA zone, since we are going to
* be pinning these entries, we might as well move them out
@@ -1652,8 +1649,6 @@ check_again:
}
}
}
-
- i += step;
}
if (!list_empty(&cma_page_list)) {
_
Patches currently in -mm which might be from pasha.tatashin@soleen.com are
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2021-05-08 22:50 [merged] mm-gup-check-every-subpage-of-a-compound-page-during-isolation.patch removed from -mm tree akpm
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