On Fri, 11 May 2007, Hugh Dickins wrote: > On Thu, 10 May 2007, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > From: Hugh Dickins <hugh@xxxxxxxxxxx> > > > > CONFIG_MODULES=y > > CONFIG_SCSI=y > > CONFIG_SCSI_SCAN_ASYNC=y > > CONFIG_SCSI_WAIT_SCAN=m > > > > 2.6.21-rc5-mm2 VFS panics unable to find my root on /dev/sda2, but boots > > okay if I change drivers/scsi/Kconfig to "default y" instead of "default m" > > for SCSI_WAIT_SCAN. > > > > Make sure there's a late_initcall to scsi_complete_async_scans when it's > > built in, so a monolithic SCSI_SCAN_ASYNC kernel can rely on the scans > > being completed before trying to mount root, even if they're slow. > > Thanks for sending this through to James again, Andrew. > I'd been gearing up to report it to the regression police: > it's certainly still a problem in 2.6.21-git. And still a problem in 2.6.22-rc1-git7. Any further news on this regression since 2.6.21? I was hoping that a fix for 2.6.22-rc2 would emerge in the course of the "Asynchronous scsi scanning" thread, but that doesn't appear to be heading in any useful direction. It wouldn't be a problem for me to undo my CONFIG_SCSI_SCAN_ASYNC=y, but it would still be a little regressive. I thought a late_initcall was guaranteed to be called after all the potential-root scsi scans had been started; but admit I'm ignorant of both initcall sequencing and scsi probing. Would a late_initcall_sync or a rootfs_initcall be more to the point? But ignore my gropings, I'd rather be testing what you believe to be the right fix. Thanks, Hugh > > > > > [akpm@xxxxxxxxxxxxxxxxxxxx: build fixes] > > Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx> > > Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxx> > > --- > > James sayeth "This isn't the right fix ... this has to be invoked last in the > > call sequence ... I can't see another way of doing this except yet another > > file added as a final component to the link." > > I didn't reply to James' mail at the time, hoping "the right fix" was > about to follow. I don't see what's wrong with the late_initcall myself. > > Hugh > > > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > --- > > > > drivers/scsi/scsi_scan.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff -puN drivers/scsi/scsi_scan.c~scsi-fix-config_scsi_wait_scan=m drivers/scsi/scsi_scan.c > > --- a/drivers/scsi/scsi_scan.c~scsi-fix-config_scsi_wait_scan=m > > +++ a/drivers/scsi/scsi_scan.c > > @@ -184,6 +184,15 @@ int scsi_complete_async_scans(void) > > /* Only exported for the benefit of scsi_wait_scan */ > > EXPORT_SYMBOL_GPL(scsi_complete_async_scans); > > > > +#ifndef MODULE > > +/* > > + * For async scanning we need to wait for all the scans to complete before > > + * trying to mount the root fs. Otherwise non-modular drivers may not be ready > > + * yet. > > + */ > > +late_initcall(scsi_complete_async_scans); > > +#endif > > + > > /** > > * scsi_unlock_floptical - unlock device via a special MODE SENSE command > > * @sdev: scsi device to send command to > > _ - 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
