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Subject[PATCH 31/41] mm: prevent do_swap_page from handling page faults under VMA lock
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Due to the possibility of do_swap_page dropping mmap_lock, abort fault
handling under VMA lock and retry holding mmap_lock. This can be handled
more gracefully in the future.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Laurent Dufour <laurent.dufour@fr.ibm.com>
---
mm/memory.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 2560524ad7f4..20806bc8b4eb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3707,6 +3707,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
if (!pte_unmap_same(vmf))
goto out;

+ if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+ ret = VM_FAULT_RETRY;
+ goto out;
+ }
+
entry = pte_to_swp_entry(vmf->orig_pte);
if (unlikely(non_swap_entry(entry))) {
if (is_migration_entry(entry)) {
--
2.39.0
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