The patch titled
Subject: mm: madvise: skip unmapped vma holes passed to process_madvise
has been added to the -mm tree. Its filename is
mm-madvise-skip-unmapped-vma-holes-passed-to-process_madvise.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-madvise-skip-unmapped-vma-holes-passed-to-process_madvise.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-madvise-skip-unmapped-vma-holes-passed-to-process_madvise.patch
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------------------------------------------------------
From: Charan Teja Kalla <quic_charante@xxxxxxxxxxx>
Subject: mm: madvise: skip unmapped vma holes passed to process_madvise
The process_madvise() system call is expected to skip holes in vma passed
through 'struct iovec' vector list. But do_madvise, which
process_madvise() calls for each vma, returns ENOMEM in case of unmapped
holes, despite the VMA is processed.
Thus process_madvise() should treat ENOMEM as expected and consider the
VMA passed to as processed and continue processing other vma's in the
vector list. Returning -ENOMEM to user, despite the VMA is processed,
will be unable to figure out where to start the next madvise.
Link: https://lkml.kernel.org/r/4f091776142f2ebf7b94018146de72318474e686.1647008754.git.quic_charante@xxxxxxxxxxx
Fixes: ecb8ac8b1f14("mm/madvise: introduce process_madvise() syscall: an external memory hinting API")
Signed-off-by: Charan Teja Kalla <quic_charante@xxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nadav Amit <nadav.amit@xxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/madvise.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/mm/madvise.c~mm-madvise-skip-unmapped-vma-holes-passed-to-process_madvise
+++ a/mm/madvise.c
@@ -1428,9 +1428,16 @@ SYSCALL_DEFINE5(process_madvise, int, pi
while (iov_iter_count(&iter)) {
iovec = iov_iter_iovec(&iter);
+ /*
+ * do_madvise returns ENOMEM if unmapped holes are present
+ * in the passed VMA. process_madvise() is expected to skip
+ * unmapped holes passed to it in the 'struct iovec' list
+ * and not fail because of them. Thus treat -ENOMEM return
+ * from do_madvise as valid and continue processing.
+ */
ret = do_madvise(mm, (unsigned long)iovec.iov_base,
iovec.iov_len, behavior);
- if (ret < 0)
+ if (ret < 0 && ret != -ENOMEM)
break;
iov_iter_advance(&iter, iovec.iov_len);
}
_
Patches currently in -mm which might be from quic_charante@xxxxxxxxxxx are
mm-vmscan-fix-documentation-for-page_check_references.patch
mm-madvise-return-correct-bytes-advised-with-process_madvise.patch
mm-madvise-skip-unmapped-vma-holes-passed-to-process_madvise.patch
