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Groups > linux.kernel > #1372091
| From | Kent Overstreet <kent.overstreet@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs |
| Date | 2016-04-06 02:30 +0200 |
| Message-ID | <rkJw5-3LU-3@gated-at.bofh.it> (permalink) |
| References | <rkDh0-7Hy-13@gated-at.bofh.it> <rkDTJ-8d1-39@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Apr 05, 2016 at 11:27:21AM -0700, Shaohua Li wrote: > On Wed, Apr 06, 2016 at 01:44:06AM +0800, Ming Lei wrote: > > After arbitrary bio size is supported, the incoming bio may > > be very big. We have to split the bio into small bios so that > > each holds at most BIO_MAX_PAGES bvecs for safety reason, such > > as bio_clone(). > > > > This patch fixes the following kernel crash: > > > > > [ 172.660142] BUG: unable to handle kernel NULL pointer dereference at > > > 0000000000000028 > > > [ 172.660229] IP: [<ffffffff811e53b4>] bio_trim+0xf/0x2a > > > [ 172.660289] PGD 7faf3e067 PUD 7f9279067 PMD 0 > > > [ 172.660399] Oops: 0000 [#1] SMP > > > [...] > > > [ 172.664780] Call Trace: > > > [ 172.664813] [<ffffffffa007f3be>] ? raid1_make_request+0x2e8/0xad7 [raid1] > > > [ 172.664846] [<ffffffff811f07da>] ? blk_queue_split+0x377/0x3d4 > > > [ 172.664880] [<ffffffffa005fb5f>] ? md_make_request+0xf6/0x1e9 [md_mod] > > > [ 172.664912] [<ffffffff811eb860>] ? generic_make_request+0xb5/0x155 > > > [ 172.664947] [<ffffffffa0445c89>] ? prio_io+0x85/0x95 [bcache] > > > [ 172.664981] [<ffffffffa0448252>] ? register_cache_set+0x355/0x8d0 [bcache] > > > [ 172.665016] [<ffffffffa04497d3>] ? register_bcache+0x1006/0x1174 [bcache] > > > > Fixes: 54efd50(block: make generic_make_request handle arbitrarily sized bios) > > this bug is introduced by d2be537c3ba > > Reported-by: Sebastian Roesner <sroesner-kernelorg@roesner-online.de> > > Reported-by: Eric Wheeler <bcache@lists.ewheeler.net> > > Cc: stable@vger.kernel.org (4.2+) > > Cc: Shaohua Li <shli@fb.com> > > Signed-off-by: Ming Lei <ming.lei@canonical.com> > > --- > > I can reproduce the issue and verify the fix by the following approach: > > - create one raid1 over two virtio-blk > > - build bcache device over the above raid1 and another cache device. > > - set cache mode as writeback > > - run random write over ext4 on the bcache device > > - then the crash can be triggered > > can you explain why this is better than my original patch? Shaohua, what was your original patch? I'm sorry, I know I saw it at one point but I can't remember what it was. I didn't see Jeff's patch that introduced this bug until your email just now. Argh. Jeff, "block: bump BLK_DEF_MAX_SECTORS to 2560" doesn't make much sense as far as I can tell without changing the BIO_MAX_PAGES too - that's probably why you weren't seeing much performance increase from that patch... But BLK_DEF_MAX_SECTORS should not have been enforcing the BIO_MAX_PAGES limit so that patch was not at fault.
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[PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-05 19:50 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Shaohua Li <shli@fb.com> - 2016-04-05 20:30 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 02:30 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 02:40 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 02:50 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 03:10 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Shaohua Li <shli@fb.com> - 2016-04-06 03:10 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Shaohua Li <shli@fb.com> - 2016-04-06 02:50 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Shaohua Li <shli@fb.com> - 2016-04-06 02:40 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 02:50 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Shaohua Li <shli@fb.com> - 2016-04-06 03:10 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 03:20 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 02:40 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 03:00 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 03:20 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 03:30 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 03:30 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 04:00 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 04:30 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 04:40 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 04:50 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 05:00 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 05:00 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Kent Overstreet <kent.overstreet@gmail.com> - 2016-04-06 04:40 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 04:40 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-06 03:10 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Eric Wheeler <bcache@lists.ewheeler.net> - 2016-04-07 03:50 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Eric Wheeler <bcache@lists.ewheeler.net> - 2016-04-07 03:40 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-07 03:50 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Eric Wheeler <bcache@lists.ewheeler.net> - 2016-04-07 04:00 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-07 04:20 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Eric Wheeler <bcache@lists.ewheeler.net> - 2016-04-08 01:30 +0200
Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs Ming Lei <ming.lei@canonical.com> - 2016-04-08 02:30 +0200
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