The patch titled
Subject: mm/mempolicy: allow lookup_node() to handle fatal signal
has been added to the -mm tree. Its filename is
mm-mempolicy-allow-lookup_node-to-handle-fatal-signal.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-mempolicy-allow-lookup_node-to-handle-fatal-signal.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-mempolicy-allow-lookup_node-to-handle-fatal-signal.patch
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------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: mm/mempolicy: allow lookup_node() to handle fatal signal
lookup_node() uses gup to pin the page and get node information. It
checks against ret>=0 assuming the page will be filled in. However it's
also possible that gup will return zero, for example, when the thread is
quickly killed with a fatal signal. Teach lookup_node() to gracefully
return an error -EFAULT if it happens.
Link: http://lkml.kernel.org/r/20200407004745.GA48345@xz-x1
Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times")
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Reported-by: syzbot+693dc11fcb53120b5559@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/mm/mempolicy.c~mm-mempolicy-allow-lookup_node-to-handle-fatal-signal
+++ a/mm/mempolicy.c
@@ -902,7 +902,10 @@ static int lookup_node(struct mm_struct
int locked = 1;
err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked);
- if (err >= 0) {
+ if (err == 0) {
+ /* E.g. GUP interupted by fatal signal */
+ err = -EFAULT;
+ } else if (err > 0) {
err = page_to_nid(p);
put_page(p);
}
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-mempolicy-allow-lookup_node-to-handle-fatal-signal.patch
mm-merge-parameters-for-change_protection.patch
userfaultfd-wp-apply-_page_uffd_wp-bit.patch
userfaultfd-wp-drop-_page_uffd_wp-properly-when-fork.patch
userfaultfd-wp-add-pmd_swp_uffd_wp-helpers.patch
userfaultfd-wp-support-swap-and-page-migration.patch
khugepaged-skip-collapse-if-uffd-wp-detected.patch
userfaultfd-wp-dont-wake-up-when-doing-write-protect.patch
userfaultfd-wp-declare-_uffdio_writeprotect-conditionally.patch
userfaultfd-selftests-refactor-statistics.patch
userfaultfd-selftests-add-write-protect-test.patch
