The patch titled
Subject: mm: fix maybe-uninitialized warning in section_deactivate()
has been added to the -mm tree. Its filename is
mm-support-section-unaligned-zone_device-memory-ranges-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-support-section-unaligned-zone_device-memory-ranges-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-support-section-unaligned-zone_device-memory-ranges-fix.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: mm: fix maybe-uninitialized warning in section_deactivate()
gcc cannot track the combined state of the 'mask' variable across the
barrier in pgdat_resize_unlock() at compile time, so it warns that we
can run into undefined behavior:
mm/sparse.c: In function 'section_deactivate':
mm/sparse.c:802:7: error: 'early_section' may be used uninitialized in this function [-Werror=maybe-uninitialized]
We know that this can't happen because the spin_unlock() doesn't
affect the mask variable, so this is a false-postive warning, but
rearranging the code to bail out earlier here makes it obvious
to the compiler as well.
Fixes: mmotm ("mm: support section-unaligned ZONE_DEVICE memory ranges")
Link: http://lkml.kernel.org/r/20170123165156.854464-1-arnd@xxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/sparse.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff -puN mm/sparse.c~mm-support-section-unaligned-zone_device-memory-ranges-fix mm/sparse.c
--- a/mm/sparse.c~mm-support-section-unaligned-zone_device-memory-ranges-fix
+++ a/mm/sparse.c
@@ -807,23 +807,24 @@ static void section_deactivate(struct pg
unsigned long mask = section_active_mask(pfn, nr_pages), flags;
pgdat_resize_lock(pgdat, &flags);
- if (!ms->usage) {
- mask = 0;
- } else if ((ms->usage->map_active & mask) != mask) {
- WARN(1, "section already deactivated active: %#lx mask: %#lx\n",
- ms->usage->map_active, mask);
- mask = 0;
- } else {
- early_section = is_early_section(ms);
- ms->usage->map_active ^= mask;
- if (ms->usage->map_active == 0) {
- usage = ms->usage;
- ms->usage = NULL;
- memmap = sparse_decode_mem_map(ms->section_mem_map,
- section_nr);
- ms->section_mem_map = 0;
- }
+ if (!ms->usage ||
+ WARN((ms->usage->map_active & mask) != mask,
+ "section already deactivated active: %#lx mask: %#lx\n",
+ ms->usage->map_active, mask)) {
+ pgdat_resize_unlock(pgdat, &flags);
+ return;
}
+
+ early_section = is_early_section(ms);
+ ms->usage->map_active ^= mask;
+ if (ms->usage->map_active == 0) {
+ usage = ms->usage;
+ ms->usage = NULL;
+ memmap = sparse_decode_mem_map(ms->section_mem_map,
+ section_nr);
+ ms->section_mem_map = 0;
+ }
+
pgdat_resize_unlock(pgdat, &flags);
/*
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
memstick-core-avoid-wnonnull-warning.patch
mm-support-section-unaligned-zone_device-memory-ranges-fix.patch
lib-add-config_test_sort-to-enable-self-test-of-sort-fix.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
