Buffer bouncing is needed only when memory exists above the lowmem region,
i.e., when max_low_pfn < max_pfn. The previous check (max_low_pfn >=
max_pfn) was inverted and prevented bouncing when it could actually be
required.
Note that bouncing depends on CONFIG_HIGHMEM, which is typically enabled
on 32-bit ARM where not all memory is permanently mapped into the kernel’s
lowmem region.
Fixes: 9bb33f24abbd0 ("block: refactor the bounce buffering code")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Hardeep Sharma <quic_hardshar@xxxxxxxxxxx>
---
Changelog v1..v2:
* Updated subject line
block/blk.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk.h b/block/blk.h
index 67915b04b3c1..f8a1d64be5a2 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -383,7 +383,7 @@ static inline bool blk_queue_may_bounce(struct request_queue *q)
{
return IS_ENABLED(CONFIG_BOUNCE) &&
q->limits.bounce == BLK_BOUNCE_HIGH &&
- max_low_pfn >= max_pfn;
+ max_low_pfn < max_pfn;
}
static inline struct bio *blk_queue_bounce(struct bio *bio,
--
2.25.1
