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| author | Michal Hocko <mhocko@suse.com> | 2020-06-04 02:03:25 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-04 06:09:49 +0300 |
| commit | 2d3a36a47964371101d9a71691c18d59ee611e87 (patch) | |
| tree | 7095a011438bf9ee1fac60a18ce6bb336b19d2f3 /mm/mempolicy.c | |
| parent | 5b94ce2fcae2542c4d5d49176fa23eea638dc7b6 (diff) | |
| download | linux-2d3a36a47964371101d9a71691c18d59ee611e87.tar.xz | |
mm, mempolicy: fix up gup usage in lookup_node
ba841078cd05 ("mm/mempolicy: Allow lookup_node() to handle fatal signal")
has added a special casing for 0 return value because that was a possible
gup return value when interrupted by fatal signal. This has been fixed by
ae46d2aa6a7f ("mm/gup: Let __get_user_pages_locked() return -EINTR for
fatal signal") in the mean time so ba841078cd05 can be reverted.
This patch however doesn't go all the way to revert it because the check
for 0 is wrong and confusing here. Firstly it is inherently unsafe to
access the page when get_user_pages_locked returns 0 (aka no page
returned).
Fortunatelly this will not happen because get_user_pages_locked will not
return 0 when nr_pages > 0 unless FOLL_NOWAIT is specified which is not
the case here. Document this potential error code in gup code while we
are at it.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Xu <peterx@redhat.com>
Link: http://lkml.kernel.org/r/20200421071026.18394-1-mhocko@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 48ba9729062e..1965e2681877 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -927,10 +927,7 @@ static int lookup_node(struct mm_struct *mm, unsigned long addr) int locked = 1; err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked); - if (err == 0) { - /* E.g. GUP interrupted by fatal signal */ - err = -EFAULT; - } else if (err > 0) { + if (err > 0) { err = page_to_nid(p); put_page(p); } |