The patch titled
Subject: mm/memory.c: allow different return codes for copy_nonpresent_pte()
has been added to the -mm tree. Its filename is
mm-memoryc-allow-different-return-codes-for-copy_nonpresent_pte.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-memoryc-allow-different-return-codes-for-copy_nonpresent_pte.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-memoryc-allow-different-return-codes-for-copy_nonpresent_pte.patch
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------------------------------------------------------
From: Alistair Popple <apopple@xxxxxxxxxx>
Subject: mm/memory.c: allow different return codes for copy_nonpresent_pte()
Currently if copy_nonpresent_pte() returns a non-zero value it is assumed
to be a swap entry which requires further processing outside the loop in
copy_pte_range() after dropping locks. This prevents other values being
returned to signal conditions such as failure which a subsequent change
requires.
Instead make copy_nonpresent_pte() return an error code if further
processing is required and read the value for the swap entry in the main
loop under the ptl.
Link: https://lkml.kernel.org/r/20210524132725.12697-7-apopple@xxxxxxxxxx
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/mm/memory.c~mm-memoryc-allow-different-return-codes-for-copy_nonpresent_pte
+++ a/mm/memory.c
@@ -718,7 +718,7 @@ copy_nonpresent_pte(struct mm_struct *ds
if (likely(!non_swap_entry(entry))) {
if (swap_duplicate(entry) < 0)
- return entry.val;
+ return -EAGAIN;
/* make sure dst_mm is on swapoff's mmlist. */
if (unlikely(list_empty(&dst_mm->mmlist))) {
@@ -974,11 +974,13 @@ again:
continue;
}
if (unlikely(!pte_present(*src_pte))) {
- entry.val = copy_nonpresent_pte(dst_mm, src_mm,
- dst_pte, src_pte,
- src_vma, addr, rss);
- if (entry.val)
+ ret = copy_nonpresent_pte(dst_mm, src_mm,
+ dst_pte, src_pte,
+ src_vma, addr, rss);
+ if (ret == -EAGAIN) {
+ entry = pte_to_swp_entry(*src_pte);
break;
+ }
progress += 8;
continue;
}
_
Patches currently in -mm which might be from apopple@xxxxxxxxxx are
mm-remove-special-swap-entry-functions.patch
mm-swapops-rework-swap-entry-manipulation-code.patch
mm-rmap-split-try_to_munlock-from-try_to_unmap.patch
mm-rmap-split-migration-into-its-own-function.patch
mm-rename-migrate_pgmap_owner.patch
mm-memoryc-allow-different-return-codes-for-copy_nonpresent_pte.patch
mm-device-exclusive-memory-access.patch
mm-selftests-for-exclusive-device-memory.patch
nouveau-svm-refactor-nouveau_range_fault.patch
nouveau-svm-implement-atomic-svm-access.patch
