On Wed, 27 Aug 2014 08:07:29 -0600 Jens Axboe <ax...@kernel.dk> wrote: > On 08/26/2014 04:01 PM, Jeff Moyer wrote: > >> Additionally, there's still quite a few places that call > >> blk_get_request() and don't check the error return if __GFP_WAIT is set. > >> Since most of the point of this is to fix segfaulting on queue dead > >> scenarios, why aren't they all converted? > > > > Odd, I thought they all were converted last I checked. They definitely > > should be. > > drivers/ide/ide-park:issue_park_cmd() (patch oddly converts just the one?!) > drivers/ide/ide-pm.c:generic_ide_suspend() > drivers/ide/ide-pm.c:generic_ide_resume() > drivers/ide/ide-cd.c:ide_cd_queue_pc() > drivers/ide/ide-atapi.c:ide_queue_pc_tail() > drivers/ide/ide-ioctls.c:ide_cmd_ioctl() > drivers/ide/ide-ioctls.c:generic_drive_reset() > drivers/ide/ide-taskfile.c:ide_raw_taskfile() > drivers/ide/ide-tape.c:idetape_queue_rw_tail() > drivers/ide/ide-cd_ioctls.c:ide_cdrom_reset() > drivers/ide/ide-disk.c:set_multcount() > drivers/ide/ide-devsets.c:ide_devset_execute() > > Why only one location in ide-park.c was converted and the rest of IDE > left untouched, I don't know. But there are definitely lots of them left > in there.
These files didn't seem to have much recent development going on, so my thinking was that if one were to bother checking the return from blk_get_request, I would update it. If the code didn't include such check in the first place, then I let it be. > There's also a bug in osd_initiator.c, _init_blk_request(). We jump to > 'out' for IS_ERR(req), which attempts to print or->request, which hasn't > been assigned yet. This is my primary concern with this patch, basically > every single of these call sites must be verified or it will do more > harm than good. Have they been? So the _init_blk_request bug has been there since c29b70f6 when the _make_request wrapper was introduced -- I missed that when inspecting the surrounding areas that the patch modified. Given the scope of the changes, I agree that the probability of introducing another bug is real. I think either you or James suggested splitting this fix into two parts: the first patch avoiding the crash I originally saw, the second modifying ABI to propagate out additional information required to discern why blk_get_request failed. As I mentioned in [1], the call chain into blk_get_request is pretty wide. I did my best trying to hunt down the callers callers callers, etc. to figure out how the returns are handled. Without testing every single site, I can't be 100% sure. In the end, I'd be happy with patch 1 to avoid the original crash report. Patch 2 was the for truth-and-beauty approach. Whether you think it's worth the risk is a judgment call on your part. [1] http://www.spinics.net/lists/kernel/msg1776335.html -- Joe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
