On Sun, 13 Oct 2019, Piergiorgio Sartor wrote: > On Mon, Sep 30, 2019 at 08:25:01PM +0200, Piergiorgio Sartor wrote: > > On Sun, Sep 29, 2019 at 09:01:48PM -0400, Alan Stern wrote: > > > On Sun, 29 Sep 2019, Piergiorgio Sartor wrote: > > > > > > > On Wed, Sep 25, 2019 at 02:31:58PM -0400, Alan Stern wrote: > > > > > On Wed, 25 Sep 2019, Piergiorgio Sartor wrote: > > > > > > > > > > > On Mon, Aug 26, 2019 at 07:38:33PM +0200, Piergiorgio Sartor wrote: > > > > > > > On Tue, Aug 20, 2019 at 06:37:22PM +0200, Piergiorgio Sartor > > > > > > > wrote: > > > > > > > > On Tue, Aug 20, 2019 at 09:23:26AM +0200, Christoph Hellwig > > > > > > > > wrote: > > > > > > > > > On Mon, Aug 19, 2019 at 10:14:25AM -0400, Alan Stern wrote: > > > > > > > > > > Let's bring this to the attention of some more people. > > > > > > > > > > > > > > > > > > > > It looks like the bug that was supposed to be fixed by > > > > > > > > > > commit > > > > > > > > > > d74ffae8b8dd ("usb-storage: Add a limitation for > > > > > > > > > > blk_queue_max_hw_sectors()"), which is part of 5.2.5, but > > > > > > > > > > apparently > > > > > > > > > > the bug still occurs. > > > > > > > > > > > > > > > > > > Piergiorgio, > > > > > > > > > > > > > > > > > > can you dump the content of max_hw_sectors_kb file for your > > > > > > > > > USB storage > > > > > > > > > device and send that to this thread? > > > > > > > > > > > > > > > > Hi all, > > > > > > > > > > > > > > > > for both kernels, 5.1.20 (working) and 5.2.8 (not working), > > > > > > > > the content of /sys/dev/x:y/queue/max_hw_sectors_kb is 512 > > > > > > > > for USB storage devices (2.0 and 3.0). > > > > > > > > > > > > > > > > This is for the PC showing the issue. > > > > > > > > > > > > > > > > In an other PC, which does not show the issus at the moment, > > > > > > > > the values are 120, for USB2.0, and 256, for USB3.0. > > > > > > > > One thing you can try is git bisect from 5.1.20 (or maybe just 5.1.0) > > > > > > > > > > to 5.2.8. If you can identify a particular commit which caused the > > > > > problem to start, that would help. > > > > > > > > OK, I tried a bisect (2 days compilations...). > > > > Assuming I've done everything correctly (how to > > > > test this? How to remove the guilty patch?), this > > > > was the result: > > > > > > > > 09324d32d2a0843e66652a087da6f77924358e62 is the first bad commit > > > > commit 09324d32d2a0843e66652a087da6f77924358e62 > > > > Author: Christoph Hellwig <h...@lst.de> > > > > Date: Tue May 21 09:01:41 2019 +0200 > > > > > > > > block: force an unlimited segment size on queues with a virt > > > > boundary > > > > > > > > We currently fail to update the front/back segment size in the bio > > > > when > > > > deciding to allow an otherwise gappy segement to a device with a > > > > virt boundary. The reason why this did not cause problems is that > > > > devices with a virt boundary fundamentally don't use segments as we > > > > know it and thus don't care. Make that assumption formal by forcing > > > > an unlimited segement size in this case. > > > > > > > > Fixes: f6970f83ef79 ("block: don't check if adjacent bvecs in one > > > > bio can be mergeable") > > > > Signed-off-by: Christoph Hellwig <h...@lst.de> > > > > Reviewed-by: Ming Lei <ming....@redhat.com> > > > > Reviewed-by: Hannes Reinecke <h...@suse.com> > > > > Signed-off-by: Jens Axboe <ax...@kernel.dk> > > > > > > > > :040000 040000 57ba04a02f948022c0f6ba24bfa36f3b565b2440 > > > > 8c925f71ce75042529c001bf244b30565d19ebf3 M block > > > > > > > > What to do now? > > > > > > Here's how to verify that the bisection got a correct result. First, > > > do a git checkout of commit 09324d32d2a0, build the kernel, and make > > > sure that it exhibits the problem. > > > > > > Next, have git write out the contents of that commit in the form of a > > > patch (git show commit-id >patchfile), and revert it (git apply -R > > > patchfile). Build the kernel from that tree, and make sure that it > > > does not exhibit the problem. If it doesn't, you have definitely shown > > > that this commit is the cause (or at least, is _one_ of the causes). > > > > I tried as suggested, i.e. jumping to commit > > 09324d32d2a0843e66652a087da6f77924358e62, testing, > > removing the patch, testing. > > The result was as expected. > > I was able to reproduce the issue with the commit, > > I was not able to reproduce it without. > > It seems this patch / commit is causing the problem. > > Directly or indirectly. > > > > What are the next steps? > > Hi all, > > I tested kernel 5.3.5 (Fedora kernel-5.3.5-200.fc30.x86_64), > with same problematic results. > > Again, what should be done now? > Could you please revert the patch? > > Or is there something else to check?
Here is one more thing you can try. I have no idea whether it will make any difference, but the Changelog entry for the patch you identified suggests that it might help. Alan Stern Index: usb-devel/drivers/usb/storage/scsiglue.c =================================================================== --- usb-devel.orig/drivers/usb/storage/scsiglue.c +++ usb-devel/drivers/usb/storage/scsiglue.c @@ -68,7 +68,6 @@ static const char* host_info(struct Scsi static int slave_alloc (struct scsi_device *sdev) { struct us_data *us = host_to_us(sdev->host); - int maxp; /* * Set the INQUIRY transfer length to 36. We don't use any of @@ -78,15 +77,6 @@ static int slave_alloc (struct scsi_devi sdev->inquiry_len = 36; /* - * USB has unusual scatter-gather requirements: the length of each - * scatterlist element except the last must be divisible by the - * Bulk maxpacket value. Fortunately this value is always a - * power of 2. Inform the block layer about this requirement. - */ - maxp = usb_maxpacket(us->pusb_dev, us->recv_bulk_pipe, 0); - blk_queue_virt_boundary(sdev->request_queue, maxp - 1); - - /* * Some host controllers may have alignment requirements. * We'll play it safe by requiring 512-byte alignment always. */