All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: syzbot <syzbot+e58112d71f77113ddb7b@syzkaller.appspotmail.com>,
	aarcange@redhat.com, akpm@linux-foundation.org,
	christian@brauner.io, davem@davemloft.net, ebiederm@xmission.com,
	elena.reshetova@intel.com, guro@fb.com, hch@infradead.org,
	james.bottomley@hansenpartnership.com, jglisse@redhat.com,
	keescook@chromium.org, ldv@altlinux.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-parisc@vger.kernel.org, luto@amacapital.net,
	mhocko@suse.com, mingo@kernel.org, namit@vmware.com,
	peterz@infradead.org, syzkaller-bugs@googlegroups.com,
	viro@zeniv.linux.org.uk, wad@chromium.org
Subject: Re: WARNING in __mmdrop
Date: Tue, 23 Jul 2019 06:42:38 -0400	[thread overview]
Message-ID: <20190723062842-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <e2e01a05-63d8-4388-2bcd-b2be3c865486@redhat.com>

On Tue, Jul 23, 2019 at 04:42:19PM +0800, Jason Wang wrote:
> > So how about this: do exactly what you propose but as a 2 patch series:
> > start with the slow safe patch, and add then return uaddr optimizations
> > on top. We can then more easily reason about whether they are safe.
> 
> 
> If you stick, I can do this.

So I definitely don't insist but I'd like us to get back to where
we know existing code is very safe (if not super fast) and
optimizing from there.  Bugs happen but I'd like to see a bisect
giving us "oh it's because of XYZ optimization" and not the
general "it's somewhere within this driver" that we are getting
now.

Maybe the way to do this is to revert for this release cycle
and target the next one. What do you think?

-- 
MST

WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: mhocko@suse.com, peterz@infradead.org, ldv@altlinux.org,
	james.bottomley@hansenpartnership.com, linux-mm@kvack.org,
	namit@vmware.com, mingo@kernel.org, elena.reshetova@intel.com,
	keescook@chromium.org, aarcange@redhat.com, davem@davemloft.net,
	hch@infradead.org, christian@brauner.io,
	syzbot <syzbot+e58112d71f77113ddb7b@syzkaller.appspotmail.com>,
	syzkaller-bugs@googlegroups.com, jglisse@redhat.com,
	viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org,
	wad@chromium.org, linux-parisc@vger.kernel.org,
	linux-kernel@vger.kernel.org, luto@amacapital.net,
	ebiederm@xmission.com, akpm@linux-foundation.org, guro@fb.com
Subject: Re: WARNING in __mmdrop
Date: Tue, 23 Jul 2019 06:42:38 -0400	[thread overview]
Message-ID: <20190723062842-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <e2e01a05-63d8-4388-2bcd-b2be3c865486@redhat.com>

On Tue, Jul 23, 2019 at 04:42:19PM +0800, Jason Wang wrote:
> > So how about this: do exactly what you propose but as a 2 patch series:
> > start with the slow safe patch, and add then return uaddr optimizations
> > on top. We can then more easily reason about whether they are safe.
> 
> 
> If you stick, I can do this.

So I definitely don't insist but I'd like us to get back to where
we know existing code is very safe (if not super fast) and
optimizing from there.  Bugs happen but I'd like to see a bisect
giving us "oh it's because of XYZ optimization" and not the
general "it's somewhere within this driver" that we are getting
now.

Maybe the way to do this is to revert for this release cycle
and target the next one. What do you think?

-- 
MST

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-07-23 10:42 UTC|newest]

Thread overview: 175+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-19  3:35 WARNING in __mmdrop syzbot
2019-07-20 10:08 ` syzbot
2019-07-20 10:08   ` syzbot
2019-07-21 10:02   ` Michael S. Tsirkin
2019-07-21 10:02     ` Michael S. Tsirkin
2019-07-21 12:18     ` Michael S. Tsirkin
2019-07-21 12:18       ` Michael S. Tsirkin
2019-07-22  5:24       ` Jason Wang
2019-07-22  5:24         ` Jason Wang
2019-07-22  8:08         ` Michael S. Tsirkin
2019-07-22  8:08           ` Michael S. Tsirkin
2019-07-23  4:01           ` Jason Wang
2019-07-23  4:01             ` Jason Wang
2019-07-23  5:01             ` Michael S. Tsirkin
2019-07-23  5:01               ` Michael S. Tsirkin
2019-07-23  5:47               ` Jason Wang
2019-07-23  5:47                 ` Jason Wang
2019-07-23  7:23                 ` Michael S. Tsirkin
2019-07-23  7:23                   ` Michael S. Tsirkin
2019-07-23  7:53                   ` Jason Wang
2019-07-23  7:53                     ` Jason Wang
2019-07-23  8:10                     ` Michael S. Tsirkin
2019-07-23  8:10                       ` Michael S. Tsirkin
2019-07-23  8:49                       ` Jason Wang
2019-07-23  8:49                         ` Jason Wang
2019-07-23  9:26                         ` Michael S. Tsirkin
2019-07-23  9:26                           ` Michael S. Tsirkin
2019-07-23 13:31                           ` Jason Wang
2019-07-23 13:31                             ` Jason Wang
2019-07-25  5:52                             ` Michael S. Tsirkin
2019-07-25  5:52                               ` Michael S. Tsirkin
2019-07-25  7:43                               ` Jason Wang
2019-07-25  7:43                                 ` Jason Wang
2019-07-25  8:28                                 ` Michael S. Tsirkin
2019-07-25  8:28                                   ` Michael S. Tsirkin
2019-07-25 13:21                                   ` Jason Wang
2019-07-25 13:21                                     ` Jason Wang
2019-07-25 13:26                                     ` Michael S. Tsirkin
2019-07-25 13:26                                       ` Michael S. Tsirkin
2019-07-25 14:25                                       ` Jason Wang
2019-07-25 14:25                                         ` Jason Wang
2019-07-26 11:49                                         ` Michael S. Tsirkin
2019-07-26 11:49                                           ` Michael S. Tsirkin
2019-07-26 12:00                                           ` Jason Wang
2019-07-26 12:00                                             ` Jason Wang
2019-07-26 12:38                                             ` Michael S. Tsirkin
2019-07-26 12:38                                               ` Michael S. Tsirkin
2019-07-26 12:53                                               ` Jason Wang
2019-07-26 12:53                                                 ` Jason Wang
2019-07-26 13:36                                                 ` Jason Wang
2019-07-26 13:36                                                   ` Jason Wang
2019-07-26 13:49                                                   ` Michael S. Tsirkin
2019-07-26 13:49                                                     ` Michael S. Tsirkin
2019-07-29  5:54                                                     ` Jason Wang
2019-07-29  5:54                                                       ` Jason Wang
2019-07-29  8:59                                                       ` Michael S. Tsirkin
2019-07-29  8:59                                                         ` Michael S. Tsirkin
2019-07-29 14:24                                                         ` Jason Wang
2019-07-29 14:24                                                           ` Jason Wang
2019-07-29 14:44                                                           ` Michael S. Tsirkin
2019-07-29 14:44                                                             ` Michael S. Tsirkin
2019-07-30  7:44                                                             ` Jason Wang
2019-07-30  7:44                                                               ` Jason Wang
2019-07-30  8:03                                                               ` Jason Wang
2019-07-30  8:03                                                                 ` Jason Wang
2019-07-30 15:08                                                               ` Michael S. Tsirkin
2019-07-30 15:08                                                                 ` Michael S. Tsirkin
2019-07-31  8:49                                                                 ` Jason Wang
2019-07-31  8:49                                                                   ` Jason Wang
2019-07-31 23:00                                                                   ` Jason Gunthorpe
2019-07-31 23:00                                                                     ` Jason Gunthorpe
2019-07-26 13:47                                                 ` Michael S. Tsirkin
2019-07-26 13:47                                                   ` Michael S. Tsirkin
2019-07-26 14:00                                                   ` Jason Wang
2019-07-26 14:00                                                     ` Jason Wang
2019-07-26 14:10                                                     ` Michael S. Tsirkin
2019-07-26 14:10                                                       ` Michael S. Tsirkin
2019-07-26 15:03                                                     ` Jason Gunthorpe
2019-07-26 15:03                                                       ` Jason Gunthorpe
2019-07-29  5:56                                                       ` Jason Wang
2019-07-29  5:56                                                         ` Jason Wang
2019-07-21 12:28     ` RFC: call_rcu_outstanding (was Re: WARNING in __mmdrop) Michael S. Tsirkin
2019-07-21 12:28       ` Michael S. Tsirkin
2019-07-21 13:17       ` Paul E. McKenney
2019-07-21 13:17         ` Paul E. McKenney
2019-07-21 17:53         ` Michael S. Tsirkin
2019-07-21 17:53           ` Michael S. Tsirkin
2019-07-21 19:28           ` Paul E. McKenney
2019-07-21 19:28             ` Paul E. McKenney
2019-07-22  7:56             ` Michael S. Tsirkin
2019-07-22  7:56               ` Michael S. Tsirkin
2019-07-22 11:57               ` Paul E. McKenney
2019-07-22 11:57                 ` Paul E. McKenney
2019-07-21 21:08         ` Matthew Wilcox
2019-07-21 21:08           ` Matthew Wilcox
2019-07-21 23:31           ` Paul E. McKenney
2019-07-21 23:31             ` Paul E. McKenney
2019-07-22  7:52             ` Michael S. Tsirkin
2019-07-22  7:52               ` Michael S. Tsirkin
2019-07-22 11:51               ` Paul E. McKenney
2019-07-22 11:51                 ` Paul E. McKenney
2019-07-22 13:41                 ` Jason Gunthorpe
2019-07-22 13:41                   ` Jason Gunthorpe
2019-07-22 15:52                   ` Paul E. McKenney
2019-07-22 15:52                     ` Paul E. McKenney
2019-07-22 16:04                     ` Jason Gunthorpe
2019-07-22 16:04                       ` Jason Gunthorpe
2019-07-22 16:15                       ` Michael S. Tsirkin
2019-07-22 16:15                         ` Michael S. Tsirkin
2019-07-22 16:15                       ` Paul E. McKenney
2019-07-22 16:15                         ` Paul E. McKenney
2019-07-22 15:14             ` Joel Fernandes
2019-07-22 15:14               ` Joel Fernandes
2019-07-22 15:47               ` Michael S. Tsirkin
2019-07-22 15:47                 ` Michael S. Tsirkin
2019-07-22 15:55                 ` Paul E. McKenney
2019-07-22 15:55                   ` Paul E. McKenney
2019-07-22 16:13                   ` Michael S. Tsirkin
2019-07-22 16:13                     ` Michael S. Tsirkin
2019-07-22 16:25                     ` Paul E. McKenney
2019-07-22 16:25                       ` Paul E. McKenney
2019-07-22 16:32                       ` Michael S. Tsirkin
2019-07-22 16:32                         ` Michael S. Tsirkin
2019-07-22 18:58                         ` Paul E. McKenney
2019-07-22 18:58                           ` Paul E. McKenney
2019-07-22  5:21     ` WARNING in __mmdrop Jason Wang
2019-07-22  5:21       ` Jason Wang
2019-07-22  8:02       ` Michael S. Tsirkin
2019-07-22  8:02         ` Michael S. Tsirkin
2019-07-23  3:55         ` Jason Wang
2019-07-23  3:55           ` Jason Wang
2019-07-23  5:02           ` Michael S. Tsirkin
2019-07-23  5:02             ` Michael S. Tsirkin
2019-07-23  5:48             ` Jason Wang
2019-07-23  5:48               ` Jason Wang
2019-07-23  7:25               ` Michael S. Tsirkin
2019-07-23  7:25                 ` Michael S. Tsirkin
2019-07-23  7:55                 ` Jason Wang
2019-07-23  7:55                   ` Jason Wang
2019-07-23  7:56               ` Michael S. Tsirkin
2019-07-23  7:56                 ` Michael S. Tsirkin
2019-07-23  8:42                 ` Jason Wang
2019-07-23  8:42                   ` Jason Wang
2019-07-23 10:27                   ` Michael S. Tsirkin
2019-07-23 10:27                     ` Michael S. Tsirkin
2019-07-23 13:34                     ` Jason Wang
2019-07-23 13:34                       ` Jason Wang
2019-07-23 15:02                       ` Michael S. Tsirkin
2019-07-23 15:02                         ` Michael S. Tsirkin
2019-07-24  2:17                         ` Jason Wang
2019-07-24  2:17                           ` Jason Wang
2019-07-24  8:05                           ` Michael S. Tsirkin
2019-07-24  8:05                             ` Michael S. Tsirkin
2019-07-24 10:08                             ` Jason Wang
2019-07-24 10:08                               ` Jason Wang
2019-07-24 18:25                               ` Michael S. Tsirkin
2019-07-24 18:25                                 ` Michael S. Tsirkin
2019-07-25  3:44                                 ` Jason Wang
2019-07-25  3:44                                   ` Jason Wang
2019-07-25  5:09                                   ` Michael S. Tsirkin
2019-07-25  5:09                                     ` Michael S. Tsirkin
2019-07-24 16:53                             ` Jason Gunthorpe
2019-07-24 16:53                               ` Jason Gunthorpe
2019-07-24 18:25                               ` Michael S. Tsirkin
2019-07-24 18:25                                 ` Michael S. Tsirkin
2019-07-23 10:42                   ` Michael S. Tsirkin [this message]
2019-07-23 10:42                     ` Michael S. Tsirkin
2019-07-23 13:37                     ` Jason Wang
2019-07-23 13:37                       ` Jason Wang
2019-07-22 14:11     ` Jason Gunthorpe
2019-07-22 14:11       ` Jason Gunthorpe
2019-07-25  6:02       ` Michael S. Tsirkin
2019-07-25  6:02         ` Michael S. Tsirkin
2019-07-25  7:44         ` Jason Wang
2019-07-25  7:44           ` Jason Wang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190723062842-mutt-send-email-mst@kernel.org \
    --to=mst@redhat.com \
    --cc=aarcange@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=christian@brauner.io \
    --cc=davem@davemloft.net \
    --cc=ebiederm@xmission.com \
    --cc=elena.reshetova@intel.com \
    --cc=guro@fb.com \
    --cc=hch@infradead.org \
    --cc=james.bottomley@hansenpartnership.com \
    --cc=jasowang@redhat.com \
    --cc=jglisse@redhat.com \
    --cc=keescook@chromium.org \
    --cc=ldv@altlinux.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mhocko@suse.com \
    --cc=mingo@kernel.org \
    --cc=namit@vmware.com \
    --cc=peterz@infradead.org \
    --cc=syzbot+e58112d71f77113ddb7b@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=viro@zeniv.linux.org.uk \
    --cc=wad@chromium.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.