From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz,
mhocko@suse.com, david@redhat.com, osalvador@suse.de,
dan.j.williams@intel.com, sashal@kernel.org,
tyhicks@linux.microsoft.com, iamjoonsoo.kim@lge.com,
mike.kravetz@oracle.com, rostedt@goodmis.org, mingo@redhat.com,
jgg@ziepe.ca, peterz@infradead.org, mgorman@suse.de,
willy@infradead.org, rientjes@google.com, jhubbard@nvidia.com,
linux-doc@vger.kernel.org, ira.weiny@intel.com,
linux-kselftest@vger.kernel.org, jmorris@namei.org
Subject: [PATCH v9 04/14] mm/gup: check for isolation errors
Date: Mon, 1 Feb 2021 10:38:17 -0500 [thread overview]
Message-ID: <20210201153827.444374-5-pasha.tatashin@soleen.com> (raw)
In-Reply-To: <20210201153827.444374-1-pasha.tatashin@soleen.com>
It is still possible that we pin movable CMA pages if there are isolation
errors and cma_page_list stays empty when we check again.
Check for isolation errors, and return success only when there are no
isolation errors, and cma_page_list is empty after checking.
Because isolation errors are transient, we retry indefinitely.
Fixes: 9a4e9f3b2d73 ("mm: update get_user_pages_longterm to migrate pages allocated from CMA region")
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
---
mm/gup.c | 60 ++++++++++++++++++++++++++++++++------------------------
1 file changed, 34 insertions(+), 26 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 88ce41f41543..7ecca2d66dff 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1555,8 +1555,8 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
struct vm_area_struct **vmas,
unsigned int gup_flags)
{
- unsigned long i;
- bool drain_allow = true;
+ unsigned long i, isolation_error_count;
+ bool drain_allow;
LIST_HEAD(cma_page_list);
long ret = nr_pages;
struct page *prev_head, *head;
@@ -1567,6 +1567,8 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
check_again:
prev_head = NULL;
+ isolation_error_count = 0;
+ drain_allow = true;
for (i = 0; i < nr_pages; i++) {
head = compound_head(pages[i]);
if (head == prev_head)
@@ -1578,25 +1580,35 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
* of the CMA zone if possible.
*/
if (is_migrate_cma_page(head)) {
- if (PageHuge(head))
- isolate_huge_page(head, &cma_page_list);
- else {
+ if (PageHuge(head)) {
+ if (!isolate_huge_page(head, &cma_page_list))
+ isolation_error_count++;
+ } else {
if (!PageLRU(head) && drain_allow) {
lru_add_drain_all();
drain_allow = false;
}
- if (!isolate_lru_page(head)) {
- list_add_tail(&head->lru, &cma_page_list);
- mod_node_page_state(page_pgdat(head),
- NR_ISOLATED_ANON +
- page_is_file_lru(head),
- thp_nr_pages(head));
+ if (isolate_lru_page(head)) {
+ isolation_error_count++;
+ continue;
}
+ list_add_tail(&head->lru, &cma_page_list);
+ mod_node_page_state(page_pgdat(head),
+ NR_ISOLATED_ANON +
+ page_is_file_lru(head),
+ thp_nr_pages(head));
}
}
}
+ /*
+ * If list is empty, and no isolation errors, means that all pages are
+ * in the correct zone.
+ */
+ if (list_empty(&cma_page_list) && !isolation_error_count)
+ return ret;
+
if (!list_empty(&cma_page_list)) {
/*
* drop the above get_user_pages reference.
@@ -1616,23 +1628,19 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
return ret > 0 ? -ENOMEM : ret;
}
- /*
- * We did migrate all the pages, Try to get the page references
- * again migrating any new CMA pages which we failed to isolate
- * earlier.
- */
- ret = __get_user_pages_locked(mm, start, nr_pages,
- pages, vmas, NULL,
- gup_flags);
-
- if (ret > 0) {
- nr_pages = ret;
- drain_allow = true;
- goto check_again;
- }
+ /* We unpinned pages before migration, pin them again */
+ ret = __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
+ NULL, gup_flags);
+ if (ret <= 0)
+ return ret;
+ nr_pages = ret;
}
- return ret;
+ /*
+ * check again because pages were unpinned, and we also might have
+ * had isolation errors and need more pages to migrate.
+ */
+ goto check_again;
}
#else
static long check_and_migrate_cma_pages(struct mm_struct *mm,
--
2.25.1
next prev parent reply other threads:[~2021-02-01 15:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-01 15:38 [PATCH v9 00/14] prohibit pinning pages in ZONE_MOVABLE Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 01/14] mm/gup: don't pin migrated cma pages in movable zone Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 02/14] mm/gup: check every subpage of a compound page during isolation Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 03/14] mm/gup: return an error on migration failure Pavel Tatashin
2021-02-01 15:38 ` Pavel Tatashin [this message]
2021-02-01 15:38 ` [PATCH v9 05/14] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 06/14] mm: apply per-task gfp constraints in fast path Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 07/14] mm: honor PF_MEMALLOC_PIN for all movable pages Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 08/14] mm/gup: do not migrate zero page Pavel Tatashin
2021-02-02 2:41 ` kernel test robot
2021-02-02 4:05 ` Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 09/14] mm/gup: migrate pinned pages out of movable zone Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 10/14] memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 11/14] mm/gup: change index type to long as it counts pages Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 12/14] mm/gup: longterm pin migration cleanup Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 13/14] selftests/vm: gup_test: fix test flag Pavel Tatashin
2021-02-01 15:38 ` [PATCH v9 14/14] selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages Pavel Tatashin
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