On Thu, Apr 04 2013 at 8:55am -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > On Thu, 4 Apr 2013, Mike Snitzer wrote: > > > I'll take a look at fixing this by deferring the scsi_dh switch until > > resume. This fix would assume multipath-tools is _not_ doing a noflush > > suspend/resume when it is switching the scsi_dh. > > > > Mike > > This won't work because scsi_dh_attach allocates memory and you can't > allocate memory when something is suspended. Ah yeah, scsi_dh->attach allocates memory for scsi_dh_data. But couldn't those scsi_dh_* attach allocations be switched from GFP_KERNEL to GFP_NOIO? > If we want to make it possible to change device handler, we need to add a > counter to "struct scsi_dh_data", increment the counter when the device > handler issues some request, decrement the counter when it finishes the > request (it may be tricky because you can't decrement it from the device > handler module because the module may be unloaded as soon as you decrement > it). Then, you wait until the counter is zero and detach the handler. Noted, but I haven't given up hope on just deferring the scsi_dh switch quite yet. Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
