If CONFIG_PREEMPT_NONE is set and the task_work chains are long, we
could be running into issues blocking others for too long. Add a
reschedule check in handle_tw_list(), and flush the ctx if we need to
reschedule.
Cc: stable(a)vger.kernel.org # 5.10+
Signed-off-by: Jens Axboe <axboe(a)kernel.dk>
---
io_uring/io_uring.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index bb8a532b051e..bc8845de2829 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1179,10 +1179,16 @@ static unsigned int handle_tw_list(struct llist_node *node,
/* if not contended, grab and improve batching */
*locked = mutex_trylock(&(*ctx)->uring_lock);
percpu_ref_get(&(*ctx)->refs);
- }
+ } else if (!*locked)
+ *locked = mutex_trylock(&(*ctx)->uring_lock);
req->io_task_work.func(req, locked);
node = next;
count++;
+ if (unlikely(need_resched())) {
+ ctx_flush_and_put(*ctx, locked);
+ *ctx = NULL;
+ cond_resched();
+ }
}
return count;
--
2.39.0
migrate_pages/mempolicy semantics state that CAP_SYS_NICE is required
to move pages shared with another process to a different node.
page_mapcount > 1 is being used to determine if a hugetlb page is shared.
However, a hugetlb page will have a mapcount of 1 if mapped by multiple
processes via a shared PMD. As a result, hugetlb pages shared by multiple
processes and mapped with a shared PMD can be moved by a process without
CAP_SYS_NICE.
To fix, check for a shared PMD if mapcount is 1. If a shared PMD is
found consider the page shared.
Fixes: e2d8cf405525 ("migrate: add hugepage migration code to migrate_pages()")
Cc: stable(a)vger.kernel.org
Signed-off-by: Mike Kravetz <mike.kravetz(a)oracle.com>
---
mm/mempolicy.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 85a34f1f3ab8..72142fbe7652 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -600,7 +600,8 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
/* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
if (flags & (MPOL_MF_MOVE_ALL) ||
- (flags & MPOL_MF_MOVE && page_mapcount(page) == 1)) {
+ (flags & MPOL_MF_MOVE && page_mapcount(page) == 1 &&
+ !hugetlb_pmd_shared(pte))) {
if (isolate_hugetlb(page, qp->pagelist) &&
(flags & MPOL_MF_STRICT))
/*
--
2.39.1