diff options
| author | Neil Brown | 2005-09-02 13:13:54 +1000 |
|---|---|---|
| committer | James Bottomley | 2005-09-09 10:29:22 -0500 |
| commit | 286f3e13a1dc7f32407629fbd7aabc8ea78c62b5 (patch) | |
| tree | 2ccc7b80111e1aac738ac67528ea3d53ac54ff0a | |
| parent | 903f4fed858a7b56b260cbd55d174fe54d188fb7 (diff) | |
[SCSI] fix possible deadlock in scsi_lib.c
If a filesystem, while writing out data, decides that it is good
to issue a cache flush on a SCSI drive (or other 'sd' device), it will
call blkdev_issue_flush which calls ->issue_flush_fn which is
scsi_issue_flush_fn.
This calls sd_issue_flush which calls sd_sync_cache, which calls
scsi_execute_request.
This will (as sshdr != NULL) call
kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL)
If memory is tight, the presence of GFP_KERNEL may cause write
requests to be sent to some filesystem to free up memory, however if
that filesystem is waiting for the issue_flush_fn to complete, you
could get a deadlock.
I wonder if it might be more appropriate to use GFP_NOIO as in the
following patch.
I wonder if it might be even more appropriate to cope better with a
kmalloc failure, especially as in this use, sd_sync_cache only will
use the sense information to print out a more informative error
message.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 77f2d444f7e0..2ad60f1dbc63 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -339,7 +339,7 @@ int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd, int result; if (sshdr) { - sense = kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL); + sense = kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO); if (!sense) return DRIVER_ERROR << 24; memset(sense, 0, SCSI_SENSE_BUFFERSIZE); |