From: Jason Gunthorpe <jgg@mellanox.com> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Doug Ledford <dledford@redhat.com>, "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [GIT PULL] Please pull RDMA subsystem changes Date: Tue, 30 Apr 2019 12:53:16 +0000 Message-ID: <20190430125310.GH3562@mellanox.com> (raw) In-Reply-To: <CAHk-=whWh+5-jGmgw2HPM8XhzXzvGcLo19UGLtqYe_teJsRgRA@mail.gmail.com> On Sun, Apr 28, 2019 at 05:09:08PM -0700, Linus Torvalds wrote: > On Sun, Apr 28, 2019 at 4:49 PM Jason Gunthorpe <jgg@mellanox.com> wrote: > > > > It is for high availability - we have situations where the hardware > > can fault and needs some kind of destructive recovery. For instance a > > firmware reboot, or a VM migration. > > > > In these designs there may be multiple cards in the system and the > > userspace application could be using both. Just because one card > > crashed we can't send SIGBUS and kill the application, that breaks the > > HA design. > > Why can't this magical application that is *so* special that it is HA > and does magic mmap's of special rdma areas just catch the SIGBUS? > > Honestly, the whole "it's for HA" excuse stinks. It stinks because you > now silently just replace the mapping with *garbage*. That's not HA, > that's just random. This should only used in cases where user space only writes to the BAR page (it is an interrupt to the device essentially), so it doesn't care that the pages are now garbage, we just need to redirect the writes away from the bar. However I think someone later on added a readable counter BAR pages to one of the devices :( So even that ideal wasn't respected. > Wouldn't it be a lot better to just get the SIGBUS, and then that > magical application knows that "oh, it's gone", and it could - in its > SIGBUS handler - just do the dummy anonymous mmap() with /dev/zero it > if it wants to? This does sound more appealing, and probably should have been done instead. All this VMA stuff has been a big pain in the long run Thanks, Jason
next prev parent reply index Thread overview: 143+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-04-28 11:52 Jason Gunthorpe 2019-04-28 16:59 ` Linus Torvalds 2019-04-28 23:49 ` Jason Gunthorpe 2019-04-29 0:09 ` Linus Torvalds 2019-04-30 12:53 ` Jason Gunthorpe [this message] 2019-04-28 18:05 ` pr-tracker-bot 2019-04-29 6:09 ` Heiko Carstens 2019-04-29 8:40 ` Jason Gunthorpe 2019-04-29 9:00 ` Michal Kubecek 2019-04-29 9:19 ` Leon Romanovsky 2019-04-29 15:42 ` Doug Ledford 2019-04-29 16:29 ` Doug Ledford -- strict thread matches above, loose matches on Subject: below -- 2021-02-22 14:59 Jason Gunthorpe 2021-02-22 18:37 ` pr-tracker-bot 2021-01-28 14:46 Jason Gunthorpe 2021-01-15 19:21 Jason Gunthorpe 2021-01-15 23:35 ` pr-tracker-bot 2020-12-16 17:57 Jason Gunthorpe 2020-12-16 21:51 ` pr-tracker-bot 2020-12-10 15:50 Jason Gunthorpe 2020-12-10 19:11 ` pr-tracker-bot 2020-11-27 14:00 Jason Gunthorpe 2020-11-27 21:21 ` pr-tracker-bot 2020-11-19 19:29 Jason Gunthorpe 2020-11-19 23:00 ` pr-tracker-bot 2020-11-05 18:16 Jason Gunthorpe 2020-11-05 20:21 ` pr-tracker-bot 2020-10-29 18:41 Jason Gunthorpe 2020-10-29 18:53 ` Linus Torvalds 2020-10-29 19:00 ` pr-tracker-bot 2020-10-16 18:51 Jason Gunthorpe 2020-10-17 18:21 ` Linus Torvalds 2020-10-17 18:42 ` Jason Gunthorpe 2020-10-17 18:22 ` pr-tracker-bot 2020-09-25 12:57 Jason Gunthorpe 2020-09-25 17:48 ` pr-tracker-bot 2020-09-10 23:38 Jason Gunthorpe 2020-09-11 18:37 ` pr-tracker-bot 2020-08-21 14:06 Jason Gunthorpe 2020-08-21 17:16 ` pr-tracker-bot 2020-08-06 18:27 Jason Gunthorpe 2020-08-07 1:55 ` pr-tracker-bot 2020-07-31 15:17 Jason Gunthorpe 2020-07-31 16:45 ` pr-tracker-bot 2020-07-24 17:47 Jason Gunthorpe 2020-07-24 21:40 ` pr-tracker-bot 2020-07-10 17:58 Jason Gunthorpe 2020-07-10 22:10 ` pr-tracker-bot 2020-06-25 17:56 Jason Gunthorpe 2020-06-25 20:15 ` pr-tracker-bot 2020-06-04 19:51 Jason Gunthorpe 2020-06-05 21:15 ` pr-tracker-bot 2020-05-29 14:15 Jason Gunthorpe 2020-05-29 21:10 ` pr-tracker-bot 2020-05-15 19:13 Jason Gunthorpe 2020-05-15 20:15 ` pr-tracker-bot 2020-04-28 19:59 Jason Gunthorpe 2020-04-28 20:40 ` pr-tracker-bot 2020-04-01 23:01 Jason Gunthorpe 2020-04-02 2:05 ` pr-tracker-bot 2020-03-26 17:31 Jason Gunthorpe 2020-03-26 17:50 ` pr-tracker-bot 2020-03-08 0:07 Jason Gunthorpe 2020-03-08 2:00 ` pr-tracker-bot 2020-02-15 21:32 Jason Gunthorpe 2020-02-16 1:20 ` pr-tracker-bot 2020-01-31 15:16 Jason Gunthorpe 2020-01-31 23:10 ` pr-tracker-bot 2020-01-10 2:16 Jason Gunthorpe 2020-01-11 14:45 ` pr-tracker-bot 2019-11-27 0:24 Jason Gunthorpe 2019-11-27 18:19 ` Linus Torvalds 2019-11-27 19:23 ` Jason Gunthorpe 2019-11-27 18:45 ` pr-tracker-bot 2019-11-14 15:16 Jason Gunthorpe 2019-11-14 16:55 ` pr-tracker-bot 2019-10-31 18:22 Jason Gunthorpe 2019-11-01 17:10 ` pr-tracker-bot 2019-10-09 14:28 Jason Gunthorpe 2019-10-09 19:30 ` pr-tracker-bot 2019-09-19 16:34 Jason Gunthorpe 2019-09-21 17:40 ` pr-tracker-bot 2019-07-30 12:15 Jason Gunthorpe 2019-07-30 20:40 ` pr-tracker-bot 2019-07-15 15:26 Jason Gunthorpe 2019-07-16 4:35 ` pr-tracker-bot 2019-06-06 20:14 Jason Gunthorpe 2019-06-07 16:45 ` pr-tracker-bot 2019-05-15 0:46 Jason Gunthorpe 2019-05-15 4:05 ` pr-tracker-bot 2019-05-09 13:37 Jason Gunthorpe 2019-05-09 16:25 ` pr-tracker-bot 2019-04-10 18:46 Jason Gunthorpe 2019-04-10 19:55 ` pr-tracker-bot 2019-03-18 1:04 Jason Gunthorpe 2019-03-19 18:15 ` pr-tracker-bot 2019-03-07 1:34 Jason Gunthorpe 2019-03-10 1:40 ` pr-tracker-bot 2019-02-21 23:07 Jason Gunthorpe 2019-02-22 18:40 ` pr-tracker-bot 2019-02-01 17:41 Jason Gunthorpe 2019-02-01 18:45 ` pr-tracker-bot 2019-01-18 3:56 Jason Gunthorpe 2019-01-18 5:35 ` pr-tracker-bot 2019-01-04 5:00 Jason Gunthorpe 2019-01-06 2:40 ` pr-tracker-bot 2018-12-24 22:16 Jason Gunthorpe 2018-12-29 1:30 ` pr-tracker-bot 2018-11-29 22:52 Jason Gunthorpe 2018-10-25 21:21 Jason Gunthorpe 2018-10-26 14:50 ` Linus Torvalds 2018-09-27 18:24 Jason Gunthorpe 2018-09-27 20:17 ` Greg Kroah-Hartman 2018-09-10 23:04 Jason Gunthorpe 2018-08-22 21:44 Jason Gunthorpe 2018-08-16 21:57 Jason Gunthorpe 2018-08-17 19:31 ` Linus Torvalds 2018-08-17 19:44 ` Linus Torvalds 2018-08-17 20:50 ` Linus Torvalds 2018-08-17 21:16 ` Jason Gunthorpe 2018-08-17 23:56 ` Linus Torvalds 2018-08-17 20:15 ` Jason Gunthorpe 2018-08-17 20:27 ` Linus Torvalds 2018-08-17 21:27 ` Jason Gunthorpe 2018-08-03 16:11 Jason Gunthorpe 2018-07-13 17:13 Jason Gunthorpe 2018-06-20 21:00 Jason Gunthorpe 2018-06-06 21:42 Jason Gunthorpe 2018-06-01 16:47 Jason Gunthorpe 2018-05-24 20:51 Jason Gunthorpe 2018-04-06 16:05 Jason Gunthorpe 2018-05-16 17:39 ` Eugene Syromiatnikov 2018-05-16 17:49 ` Jason Gunthorpe 2018-05-16 18:01 ` Eugene Syromiatnikov 2018-03-29 19:17 Jason Gunthorpe 2018-03-20 23:17 Jason Gunthorpe 2018-01-31 17:47 Jason Gunthorpe [not found] ` <20180131174735.GA18568-uk2M96/98Pc@public.gmane.org> 2018-01-31 20:11 ` Linus Torvalds [not found] ` <CA+55aFxmnW-iu1Na3QC8Ci8Q_Qdfn2Ak_9wDB6+A564R=Xn9Ag-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2018-01-31 21:04 ` Jason Gunthorpe [not found] ` <20180131210457.GE23352-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> 2018-02-01 19:12 ` Linus Torvalds [not found] ` <CA+55aFxySLoCHcmZgx2PiF6jEazVOSy=2idccRsWqOzmyK2gaw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2018-02-01 20:33 ` Jason Gunthorpe 2017-12-28 21:03 Jason Gunthorpe 2017-12-16 17:12 Jason Gunthorpe
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