linux-kernel - Re: [PATCH v2 0/4] zram: fix few sysfs races

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Date:   Fri, 21 May 2021 22:01:52 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     Minchan Kim <minchan@...nel.org>, Hannes Reinecke <hare@...e.de>,
        Douglas Gilbert <dgilbert@...erlog.com>, ngupta@...are.org,
        sergey.senozhatsky.work@...il.com, axboe@...nel.dk,
        mbenes@...e.com, jpoimboe@...hat.com, tglx@...utronix.de,
        keescook@...omium.org, jikos@...nel.org, rostedt@...dmis.org,
        peterz@...radead.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/4] zram: fix few sysfs races

On Wed, May 19, 2021 at 08:20:23PM +0000, Luis Chamberlain wrote:
> Greg,
> 
> your feedback would be appreciated here.

Appreciated where?  This is a zram patchset, what do I need to mess with
it for?



> 
> On Wed, May 19, 2021 at 01:09:09PM -0700, Minchan Kim wrote:
> > On Fri, Apr 23, 2021 at 01:11:04AM +0000, Luis Chamberlain wrote:
> > > This 2nd series documents the fixes better and includes a bdgrab() fix
> > > for the issue noted by Minchan. A general fix has been proposed for two
> > > of these issues however they are not yet deemed required upstream and so
> > > we just open code individual solutions on the driver.
> > > 
> > > Luis Chamberlain (4):
> > >   zram: fix crashes due to use of cpu hotplug multistate
> > >   zram: avoid disksize setting when device is being claimed
> > >   zram: fix deadlock with sysfs attribute usage and driver removal
> > >   zram: fix possible races between sysfs use and bdev access
> > > 
> > >  drivers/block/zram/zram_drv.c | 473 +++++++++++++++++++++++++++++-----
> > >  1 file changed, 414 insertions(+), 59 deletions(-)
> > 
> > Hi Luis,
> > 
> > First of all, I am sorry too late review. Now I see [3/4] and [4/4] would
> > be not only zram issue since you shed a light in the descriptions.
> > Yeah, that would be helpful if it could be deal with under general
> > layer but looks like arguable or would take some times at least, IIUC.
> > 
> > On the case, yeah, we could fix it for zram first until the issue will
> > bring up further. Anyway, I'd like to see some wrapper rather than annotating
> > for every sysfs files for maintainance point of view.
> > At least, could you introduce one more patch "introduce zram sysfs wrapper"
> > on top of this series to centralize the work?
> > 
> > Thanks for your works!
> 
> Since I did the work for a general fix as an alternative proof of
> concept to the ugliness reflected on those two last patches, I'd like
> instead for Greg to re-consider merging a general fix.
> 
> Greg, can you comment on technical levels why a general core fix is not
> desirable upstream for those two issues?

What issues exactly?

totally confused,

greg k-h