On Tue, Nov 25, 2014 at 10:41:04PM -0500, Mike Snitzer wrote: > On Tue, Nov 25 2014 at 8:45pm -0500, > Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > > > When dm-bufio sets out to use the bio built into a struct dm_buffer to > > issue an IO, it needs to call bio_reset after it's done with the bio > > so that we can free things attached to the bio such as the integrity > > payload. Therefore, inject our own endio callback to take care of > > the bio_reset after calling submit_io's end_io callback. > > > > Test case: > > 1. modprobe scsi_debug delay=0 dif=1 dix=199 ato=1 dev_size_mb=300 > > 2. Set up a dm-bufio client, e.g. dm-verity, on the scsi_debug device > > 3. Repeatedly read metadata and watch kmalloc-192 leak! > > > > Fix is against 3.18-rc6. > > > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > Thanks for reporting/fixing this. > > Alternatively I think we could just call bio_reset() in submit_io(), > e.g.: > > diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c > index afe7971..e7036e3 100644 > --- a/drivers/md/dm-bufio.c > +++ b/drivers/md/dm-bufio.c > @@ -579,6 +579,8 @@ static void submit_io(struct dm_buffer *b, int rw, sector_t block, > if (rw == WRITE && b->c->write_callback) > b->c->write_callback(b); > > + bio_reset(&b->bio); > + > if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE && > b->data_mode != DATA_MODE_VMALLOC) > use_inline_bio(b, rw, block, end_io); > > What do you think? I decided to call bio_reset after calling end_io so that we can free the integrity buffer as soon as we're done with the bio. Calling bio_reset just prior to the next submit_bio as this snippet does means that the integrity buffer remains attached to the bio until just before the next submit_bio call, which could be a while. Also, I think use_dmio results in a new bio being used instead of the bio embedded in the dm_buffer, so it shouldn't be necessary to reset the bio if the previous IO had use_dmio'd. --D > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
