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-rw-r--r--mm/swap.h8
-rw-r--r--mm/vmscan.c29
2 files changed, 28 insertions, 9 deletions
diff --git a/mm/swap.h b/mm/swap.h
index f8265bf0ce00..e19f185df5e2 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -50,6 +50,10 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
struct vm_fault *vmf);
+static inline unsigned int page_swap_flags(struct page *page)
+{
+ return page_swap_info(page)->flags;
+}
#else /* CONFIG_SWAP */
static inline int swap_readpage(struct page *page, bool do_poll)
{
@@ -129,5 +133,9 @@ static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
{
}
+static inline unsigned int page_swap_flags(struct page *page)
+{
+ return 0;
+}
#endif /* CONFIG_SWAP */
#endif /* _MM_SWAP_H */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b1b91d5b9f49..95ebcb5b3e12 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1502,6 +1502,22 @@ static unsigned int demote_page_list(struct list_head *demote_pages,
return nr_succeeded;
}
+static bool may_enter_fs(struct page *page, gfp_t gfp_mask)
+{
+ if (gfp_mask & __GFP_FS)
+ return true;
+ if (!PageSwapCache(page) || !(gfp_mask & __GFP_IO))
+ return false;
+ /*
+ * We can "enter_fs" for swap-cache with only __GFP_IO
+ * providing this isn't SWP_FS_OPS.
+ * ->flags can be updated non-atomicially (scan_swap_map_slots),
+ * but that will never affect SWP_FS_OPS, so the data_race
+ * is safe.
+ */
+ return !data_race(page_swap_flags(page) & SWP_FS_OPS);
+}
+
/*
* shrink_page_list() returns the number of reclaimed pages
*/
@@ -1528,7 +1544,7 @@ retry:
struct page *page;
struct folio *folio;
enum page_references references = PAGEREF_RECLAIM;
- bool dirty, writeback, may_enter_fs;
+ bool dirty, writeback;
unsigned int nr_pages;
cond_resched();
@@ -1553,9 +1569,6 @@ retry:
if (!sc->may_unmap && page_mapped(page))
goto keep_locked;
- may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
- (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
-
/*
* The number of dirty pages determines if a node is marked
* reclaim_congested. kswapd will stall and start writing
@@ -1598,7 +1611,7 @@ retry:
* not to fs). In this case mark the page for immediate
* reclaim and continue scanning.
*
- * Require may_enter_fs because we would wait on fs, which
+ * Require may_enter_fs() because we would wait on fs, which
* may not have submitted IO yet. And the loop driver might
* enter reclaim, and deadlock if it waits on a page for
* which it is needed to do the write (loop masks off
@@ -1630,7 +1643,7 @@ retry:
/* Case 2 above */
} else if (writeback_throttling_sane(sc) ||
- !PageReclaim(page) || !may_enter_fs) {
+ !PageReclaim(page) || !may_enter_fs(page, sc->gfp_mask)) {
/*
* This is slightly racy - end_page_writeback()
* might have just cleared PageReclaim, then
@@ -1720,8 +1733,6 @@ retry:
goto activate_locked_split;
}
- may_enter_fs = true;
-
/* Adding to swap updated mapping */
mapping = page_mapping(page);
}
@@ -1792,7 +1803,7 @@ retry:
if (references == PAGEREF_RECLAIM_CLEAN)
goto keep_locked;
- if (!may_enter_fs)
+ if (!may_enter_fs(page, sc->gfp_mask))
goto keep_locked;
if (!sc->may_writepage)
goto keep_locked;