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-rw-r--r--mm/memory.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index fc8b264ec..fb83cf563 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3761,6 +3761,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
struct page *page;
struct swap_info_struct *si = NULL;
rmap_t rmap_flags = RMAP_NONE;
+ bool need_clear_cache = false;
bool exclusive = false;
swp_entry_t entry;
pte_t pte;
@@ -3822,6 +3823,20 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
if (!folio) {
if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
__swap_count(entry) == 1) {
+ /*
+ * Prevent parallel swapin from proceeding with
+ * the cache flag. Otherwise, another thread may
+ * finish swapin first, free the entry, and swapout
+ * reusing the same entry. It's undetectable as
+ * pte_same() returns true due to entry reuse.
+ */
+ if (swapcache_prepare(entry)) {
+ /* Relax a bit to prevent rapid repeated page faults */
+ schedule_timeout_uninterruptible(1);
+ goto out;
+ }
+ need_clear_cache = true;
+
/* skip swapcache */
folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
vma, vmf->address, false);
@@ -4073,6 +4088,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
unlock:
pte_unmap_unlock(vmf->pte, vmf->ptl);
out:
+ /* Clear the swap cache pin for direct swapin after PTL unlock */
+ if (need_clear_cache)
+ swapcache_clear(si, entry);
if (si)
put_swap_device(si);
return ret;
@@ -4086,6 +4104,8 @@ out_release:
folio_unlock(swapcache);
folio_put(swapcache);
}
+ if (need_clear_cache)
+ swapcache_clear(si, entry);
if (si)
put_swap_device(si);
return ret;