/* Obtain the lock on page, remove all ptes. */
static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page,
unsigned long private, struct folio *src,
- struct folio **dstp, int force, bool avoid_force_lock,
+ struct folio **dstp, int force,
enum migrate_mode mode, enum migrate_reason reason,
struct list_head *ret)
{
if (current->flags & PF_MEMALLOC)
goto out;
- /*
- * We have locked some folios and are going to wait to lock
- * this folio. To avoid a potential deadlock, let's bail
- * out and not do that. The locked folios will be moved and
- * unlocked, then we can wait to lock this folio.
- */
- if (avoid_force_lock) {
- rc = -EDEADLOCK;
- goto out;
- }
-
folio_lock(src);
}
locked = true;
/* Establish migration ptes */
VM_BUG_ON_FOLIO(folio_test_anon(src) &&
!folio_test_ksm(src) && !anon_vma, src);
- try_to_migrate(src, TTU_BATCH_FLUSH);
+ try_to_migrate(src, mode == MIGRATE_ASYNC ? TTU_BATCH_FLUSH : 0);
page_was_mapped = 1;
}
* A folio that has not been unmapped will be restored to
* right list unless we want to retry.
*/
- if (rc == -EAGAIN || rc == -EDEADLOCK)
+ if (rc == -EAGAIN)
ret = NULL;
migrate_folio_undo_src(src, page_was_mapped, anon_vma, locked, ret);
/*
* migrate_pages_batch() first unmaps folios in the from list as many as
* possible, then move the unmapped folios.
+ *
+ * We only batch migration if mode == MIGRATE_ASYNC to avoid to wait a
+ * lock or bit when we have locked more than one folio. Which may cause
+ * deadlock (e.g., for loop device). So, if mode != MIGRATE_ASYNC, the
+ * length of the from list must be <= 1.
*/
static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
free_page_t put_new_page, unsigned long private,
LIST_HEAD(dst_folios);
bool nosplit = (reason == MR_NUMA_MISPLACED);
bool no_split_folio_counting = false;
- bool avoid_force_lock;
+ VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
+ !list_empty(from) && !list_is_singular(from));
retry:
rc_saved = 0;
- avoid_force_lock = false;
retry = 1;
for (pass = 0;
pass < NR_MAX_MIGRATE_PAGES_RETRY && (retry || large_retry);
}
rc = migrate_folio_unmap(get_new_page, put_new_page, private,
- folio, &dst, pass > 2, avoid_force_lock,
- mode, reason, ret_folios);
+ folio, &dst, pass > 2, mode,
+ reason, ret_folios);
/*
* The rules are:
* Success: folio will be freed
* Unmap: folio will be put on unmap_folios list,
* dst folio put on dst_folios list
* -EAGAIN: stay on the from list
- * -EDEADLOCK: stay on the from list
* -ENOMEM: stay on the from list
* Other errno: put on ret_folios list
*/
goto out;
else
goto move;
- case -EDEADLOCK:
- /*
- * The folio cannot be locked for potential deadlock.
- * Go move (and unlock) all locked folios. Then we can
- * try again.
- */
- rc_saved = rc;
- goto move;
case -EAGAIN:
if (is_large) {
large_retry++;
stats->nr_thp_succeeded += is_thp;
break;
case MIGRATEPAGE_UNMAP:
- /*
- * We have locked some folios, don't force lock
- * to avoid deadlock.
- */
- avoid_force_lock = true;
list_move_tail(&folio->lru, &unmap_folios);
list_add_tail(&dst->lru, &dst_folios);
break;
*/
list_splice_init(from, ret_folios);
list_splice_init(&split_folios, from);
+ /*
+ * Force async mode to avoid to wait lock or bit when we have
+ * locked more than one folios.
+ */
+ mode = MIGRATE_ASYNC;
no_split_folio_counting = true;
goto retry;
}
- /*
- * We have unlocked all locked folios, so we can force lock now, let's
- * try again.
- */
- if (rc == -EDEADLOCK)
- goto retry;
-
return rc;
}
enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
{
int rc, rc_gather;
- int nr_pages;
+ int nr_pages, batch;
struct folio *folio, *folio2;
LIST_HEAD(folios);
LIST_HEAD(ret_folios);
mode, reason, &stats, &ret_folios);
if (rc_gather < 0)
goto out;
+
+ if (mode == MIGRATE_ASYNC)
+ batch = NR_MAX_BATCHED_MIGRATION;
+ else
+ batch = 1;
again:
nr_pages = 0;
list_for_each_entry_safe(folio, folio2, from, lru) {
}
nr_pages += folio_nr_pages(folio);
- if (nr_pages > NR_MAX_BATCHED_MIGRATION)
+ if (nr_pages >= batch)
break;
}
- if (nr_pages > NR_MAX_BATCHED_MIGRATION)
- list_cut_before(&folios, from, &folio->lru);
+ if (nr_pages >= batch)
+ list_cut_before(&folios, from, &folio2->lru);
else
list_splice_init(from, &folios);
rc = migrate_pages_batch(&folios, get_new_page, put_new_page, private,
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