On 07/01/2010 01:49 PM, FUJITA Tomonori wrote: > This patchset fixes page leak issue in discard commands with unprep > facility that James posted: > > http://marc.info/?l=linux-scsi&m=127791727508214&w=2 > > The 1/3 patch adds unprep facility to the block layer (identical to > what James posted). > Alternatively to this patch you could also call scsi_driver->done() on all commands. There are only two users (sd sr) it's not that bad to add an if (blk_pc_req()) inside these ->done() function. > The 2/3 patch frees a page for discard commands by using the unprep > facility. James' original patch doesn't work since it accesses to > rq->bio in q->unprep_rq_fn. We hit oops since q->unprep_rq_fn is > called when all the data buffer (req->bio and scsi_data_buffer) in the > request is freed. > > I use rq->buffer to keep track of an allocated page as the block layer > sets rq->buffer to the address of bio's page. scsi-ml (and llds) don't > use rq->buffer (rq->buffer is set to NULL). So I can't say that I like > it lots. Any other way to do that? > rq->buffer is intended for block-driver use as well as req->special. sd+scsi-ml is the block-driver here. req->special is used by scsi-ml and rq->buffer is set to NULL inside the call to scsi_setup_blk_pc_cmnd/scsi_setup_fs_cmnd. Since you set the ->buffer after the call to scsi_setup_blk_pc_cmnd you should be in the clear. I think scsi-ml should stop setting rq->buffer to NULL and leave it be for ULD use. It is left from the time that LLDs where converted to use BIOs, just to make sure out-of-tree drivers crash. Boaz > The 3/3 path just removes the dead code. > > This is against Jens' for-2.6.36. > > The git tree is also available: > > git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-misc.git unprep > > I'll update the discard FS request conversion on the top of this soon. But this can be applied independently (and fixes the memory leak). > > = > block/blk-core.c | 25 +++++++++++++++++++++++++ > block/blk-settings.c | 17 +++++++++++++++++ > drivers/scsi/scsi_lib.c | 2 +- > drivers/scsi/sd.c | 25 +++++++++++++++---------- > include/linux/blkdev.h | 4 ++++ > 5 files changed, 62 insertions(+), 11 deletions(-) > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
