The patch titled
Subject: mm/gup: don't pin migrated cma pages in movable zone
has been added to the -mm tree. Its filename is
mm-gup-dont-pin-migrated-cma-pages-in-movable-zone.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-gup-dont-pin-migrated-cma-pages-in-movable-zone.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-dont-pin-migrated-cma-pages-in-movable-zone.patch
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From: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: mm/gup: don't pin migrated cma pages in movable zone
Patch series "prohibit pinning pages in ZONE_MOVABLE", v9.
When page is pinned it cannot be moved and its physical address stays the
same until pages is unpinned.
This is useful functionality to allows userland to implementation DMA
access. For example, it is used by vfio in vfio_pin_pages().
However, this functionality breaks memory hotplug/hotremove assumptions
that pages in ZONE_MOVABLE can always be migrated.
This patch series fixes this issue by forcing new allocations during page
pinning to omit ZONE_MOVABLE, and also to migrate any existing pages from
ZONE_MOVABLE during pinning.
It uses the same scheme logic that is currently used by CMA, and extends
the functionality for all allocations.
For more information read the discussion [1] about this problem.
[1] https://lore.kernel.org/lkml/CA+CK2bBffHBxjmb9jmSKacm0fJMinyt3Nhk8Nx6iudcQSj80_w@xxxxxxxxxxxxxx
This patch (of 14):
In order not to fragment CMA the pinned pages are migrated. However, they
are migrated to ZONE_MOVABLE, which also should not have pinned pages.
Remove __GFP_MOVABLE, so pages can be migrated to zones where pinning is
allowed.
Link: https://lkml.kernel.org/r/20210201153827.444374-1-pasha.tatashin@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20210201153827.444374-2-pasha.tatashin@xxxxxxxxxx
Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>
Cc: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/gup.c~mm-gup-dont-pin-migrated-cma-pages-in-movable-zone
+++ a/mm/gup.c
@@ -1556,7 +1556,7 @@ static long check_and_migrate_cma_pages(
long ret = nr_pages;
struct migration_target_control mtc = {
.nid = NUMA_NO_NODE,
- .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_NOWARN,
+ .gfp_mask = GFP_USER | __GFP_NOWARN,
};
check_again:
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
mm-gup-dont-pin-migrated-cma-pages-in-movable-zone.patch
mm-gup-check-every-subpage-of-a-compound-page-during-isolation.patch
mm-gup-return-an-error-on-migration-failure.patch
mm-gup-check-for-isolation-errors.patch
mm-cma-rename-pf_memalloc_nocma-to-pf_memalloc_pin.patch
mm-apply-per-task-gfp-constraints-in-fast-path.patch
mm-honor-pf_memalloc_pin-for-all-movable-pages.patch
mm-gup-do-not-migrate-zero-page.patch
mm-gup-migrate-pinned-pages-out-of-movable-zone.patch
memory-hotplugrst-add-a-note-about-zone_movable-and-page-pinning.patch
mm-gup-change-index-type-to-long-as-it-counts-pages.patch
mm-gup-longterm-pin-migration-cleanup.patch
selftests-vm-gup_test-fix-test-flag.patch
selftests-vm-gup_test-test-faulting-in-kernel-and-verify-pinnable-pages.patch
