6.6-stable review patch. If anyone has any objections, please let me know.
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From: Johannes Thumshirn johannes.thumshirn@wdc.com
[ Upstream commit 7ce3e6107103214d354a16729a472f588be60572 ]
We have two reports of failed memory allocation in btrfs' code which is calling into report zones.
Both of these reports have the following signature coming from __vmalloc_area_node():
kworker/u17:5: vmalloc error: size 0, failed to allocate pages, mode:0x10dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_NORETRY|__GFP_ZERO), nodemask=(null),cpuset=/,mems_allowed=0
Further debugging showed these where allocations of one sector (512 bytes) and at least one of the reporter's systems where low on memory, so going through the overhead of allocating a vm area failed.
Switching the allocation from __vmalloc() to kvzalloc() avoids the overhead of vmalloc() on small allocations and succeeds.
Note: the buffer is already freed using kvfree() so there's no need to adjust the free path.
Cc: Qu Wenru wqu@suse.com Cc: Naohiro Aota naohiro.aota@wdc.com Link: https://github.com/kdave/btrfs-progs/issues/779 Link: https://github.com/kdave/btrfs-progs/issues/915 Fixes: 23a50861adda ("scsi: sd_zbc: Cleanup sd_zbc_alloc_report_buffer()") Signed-off-by: Johannes Thumshirn johannes.thumshirn@wdc.com Link: https://lore.kernel.org/r/20241030110253.11718-1-jth@kernel.org Reviewed-by: Damien Le Moal dlemoal@kernel.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/sd_zbc.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c index a25215507668d..203df5e53b1a8 100644 --- a/drivers/scsi/sd_zbc.c +++ b/drivers/scsi/sd_zbc.c @@ -221,8 +221,7 @@ static void *sd_zbc_alloc_report_buffer(struct scsi_disk *sdkp, bufsize = min_t(size_t, bufsize, queue_max_segments(q) << PAGE_SHIFT);
while (bufsize >= SECTOR_SIZE) { - buf = __vmalloc(bufsize, - GFP_KERNEL | __GFP_ZERO | __GFP_NORETRY); + buf = kvzalloc(bufsize, GFP_KERNEL | __GFP_NORETRY); if (buf) { *buflen = bufsize; return buf;