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authorAlistair Popple <apopple@nvidia.com>2021-06-30 18:54:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-07-01 11:06:03 -0700
commit9a5cc85c407402ae66128d31f0422a3a7ffa5c5c (patch)
tree801de2493d54996d46135d7824a16abb5b24f76e /mm
parent6b49bf6ddbb0d7992c816846acfa5fd1cf751c36 (diff)
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/20210616105937.23201-7-apopple@nvidia.com Signed-off-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory.c28
1 files changed, 17 insertions, 11 deletions
diff --git a/mm/memory.c b/mm/memory.c
index e30488e9202f..75feddbf0190 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -717,7 +717,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
if (likely(!non_swap_entry(entry))) {
if (swap_duplicate(entry) < 0)
- return entry.val;
+ return -EIO;
/* make sure dst_mm is on swapoff's mmlist. */
if (unlikely(list_empty(&dst_mm->mmlist))) {
@@ -973,12 +973,14 @@ again:
continue;
}
if (unlikely(!pte_present(*src_pte))) {
- entry.val = copy_nonpresent_pte(dst_mm, src_mm,
- dst_pte, src_pte,
- dst_vma, src_vma,
- addr, rss);
- if (entry.val)
+ ret = copy_nonpresent_pte(dst_mm, src_mm,
+ dst_pte, src_pte,
+ dst_vma, src_vma,
+ addr, rss);
+ if (ret == -EIO) {
+ entry = pte_to_swp_entry(*src_pte);
break;
+ }
progress += 8;
continue;
}
@@ -1011,20 +1013,24 @@ again:
pte_unmap_unlock(orig_dst_pte, dst_ptl);
cond_resched();
- if (entry.val) {
+ if (ret == -EIO) {
+ VM_WARN_ON_ONCE(!entry.val);
if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
ret = -ENOMEM;
goto out;
}
entry.val = 0;
- } else if (ret) {
- WARN_ON_ONCE(ret != -EAGAIN);
+ } else if (ret == -EAGAIN) {
prealloc = page_copy_prealloc(src_mm, src_vma, addr);
if (!prealloc)
return -ENOMEM;
- /* We've captured and resolved the error. Reset, try again. */
- ret = 0;
+ } else if (ret) {
+ VM_WARN_ON_ONCE(1);
}
+
+ /* We've captured and resolved the error. Reset, try again. */
+ ret = 0;
+
if (addr != end)
goto again;
out: