Re: [PATCH] block: aoe: fix page fault in freedev()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Mar 10, 2022 at 01:55:25PM +0100, Valentin Kleibel wrote:
> On 10/03/2022 13:26, Greg Kroah-Hartman wrote:
> > On Thu, Mar 10, 2022 at 01:24:38PM +0100, Valentin Kleibel wrote:
> > > On 10/03/2022 13:03, Greg Kroah-Hartman wrote:
> > > > > This patch applies to kernels 5.4 and 5.10.
> > > > 
> > > > We need a fix for Linus's tree first before we can backport anything to
> > > > older kernels.  Does this also work there?
> > > 
> > > It is fixed in Linus' tree starting with 5.14.
> > 
> > What commit fixes it there?  Why not just backport that one only?
> 
> commit 6560ec961a08 (aoe: use blk_mq_alloc_disk and blk_cleanup_disk)
> This commit uses the function blk_cleanup_disk() in freedev() in
> drivers/block/aoe/aoedev.c which fixes the issue.
> The function was introduced in f525464a8000 (block: add blk_alloc_disk and
> blk_cleanup_disk APIs):
> void blk_cleanup_disk(struct gendisk *disk)
> {
> 	blk_cleanup_queue(disk->queue);
> 	put_disk(disk);
> }
> EXPORT_SYMBOL(blk_cleanup_disk);
> 
> I tried to backport the fix to the lts kernels without introducing a new API
> by just adjusting the order of the two function calls.
> Is it preferable to introduce and use the function blk_cleanup_disk()?

I do not know, sorry.  But we prefer the upstream commits as much as
possible as one-off changes like this are almost always buggy and wrong
in the end.

Try doing the backports and see what that looks like please.

thanks,

greg k-h