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@vger.kernel.org Signed-off-by: Hardeep Sharma quic_hardshar@quicinc.com --- 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,