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mm/gup: check for isolation errors

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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.

Link: https://lkml.kernel.org/r/20210215161349.246722-5-pasha.tatashin@soleen.com
Fixes: 9a4e9f3b2d ("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>
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Pavel Tatashin 2021-05-04 18:38:49 -07:00 committed by Linus Torvalds
parent f0f4463837
commit 6e7f34ebb8
1 changed files with 34 additions and 26 deletions
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60
mm/gup.c
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@ -1608,8 +1608,8 @@ 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;
@ -1620,6 +1620,8 @@ 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)
@ -1631,25 +1633,35 @@ check_again:
* 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.
@ -1669,23 +1681,19 @@ check_again:
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,