From: Arnd Bergmann <arnd@xxxxxxxx>
commit 590347e4000356f55eb10b03ced2686bd74dab40 upstream.
gcc-6.3 and earlier show a new warning after a seemingly unrelated
change to the arm64 PAGE_KERNEL definition:
In file included from drivers/md/dm-bufio.c:14:0:
drivers/md/dm-bufio.c: In function 'alloc_buffer':
include/linux/sched/mm.h:182:56: warning: 'noio_flag' may be used uninitialized in this function [-Wmaybe-uninitialized]
current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
^
The same warning happened earlier on linux-3.18 for MIPS and I did a
workaround for that, but now it's come back.
gcc-7 and newer are apparently smart enough to figure this out, and
other architectures don't show it, so the best I could come up with is
to rework the caller slightly in a way that makes it obvious enough to
all arm64 compilers what is happening here.
Fixes: 41acec624087 ("arm64: kpti: Make use of nG dependent on arm64_kernel_unmapped_at_el0()")
Link: https://patchwork.kernel.org/patch/9692829/
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
[snitzer: moved declarations inside conditional, altered vmalloc return]
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
[nc: Backport to 4.9, adjust context for lack of 19809c2da28a]
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
---
Hi Greg,
Resending this with a proper prefix and message, in case the other one
fell through the cracks. I came across this warning when building with
Google's stock GCC 4.9 toolchain on the OnePlus 6. Context was adjusted
around lack of commit 19809c2da28a ("mm, vmalloc: use __GFP_HIGHMEM
implicitly") in 4.9. Please apply when you get a chance.
Thanks!
Nathan
drivers/md/dm-bufio.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 3ec647e8b9c6..35fd57fdeba9 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -373,9 +373,6 @@ static void __cache_size_refresh(void)
static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
enum data_mode *data_mode)
{
- unsigned noio_flag;
- void *ptr;
-
if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) {
*data_mode = DATA_MODE_SLAB;
return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask);
@@ -399,16 +396,16 @@ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
* all allocations done by this process (including pagetables) are done
* as if GFP_NOIO was specified.
*/
+ if (gfp_mask & __GFP_NORETRY) {
+ unsigned noio_flag = memalloc_noio_save();
+ void *ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM,
+ PAGE_KERNEL);
- if (gfp_mask & __GFP_NORETRY)
- noio_flag = memalloc_noio_save();
-
- ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
-
- if (gfp_mask & __GFP_NORETRY)
memalloc_noio_restore(noio_flag);
+ return ptr;
+ }
- return ptr;
+ return __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
}
/*
--
2.17.1
