From: Stephen Rust <srust@blockbridge.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Rob Townley <rob.townley@gmail.com>,
Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-scsi@vger.kernel.org, martin.petersen@oracle.com,
target-devel@vger.kernel.org, Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Sagi Grimberg <sagi@grimberg.me>,
Max Gurtovoy <maxg@mellanox.com>
Subject: Re: Data corruption in kernel 5.1+ with iSER attached ramdisk
Date: Wed, 4 Dec 2019 21:28:43 -0500 [thread overview]
Message-ID: <CAAFE1bcwcdVuzAG5+x1UNcTaa22bf0tOaT=QOWrTup98sFXxuQ@mail.gmail.com> (raw)
In-Reply-To: <20191204230225.GA26189@ming.t460p>
Hi Ming,
Thanks for all your help and insight. I really appreciate it.
> > Presumably non-brd devices, ie: real scsi devices work for these test
> > cases because they accept un-aligned buffers?
>
> Right, not every driver supports such un-aligned buffer.
Can you please clarify: does the block layer require that it is called
with 512-byte aligned buffers? If that is the case, would it make
sense for the block interface (bio_add_page() or other) to reject
buffers that are not aligned?
It seems that passing these buffers on to underlying drivers that
don't support un-aligned buffers can result in silent data corruption.
Perhaps it would be better to fail the I/O up front. This would also
help future proof the block interface when changes/new target drivers
are added.
I'm also curious how these same unaligned buffers from iSER made it to
brd and were written successfully in the pre "multi-page bvec" world.
(Just trying to understand, if you have any thoughts, as this same
test case worked fine in 4.14+ until 5.1)
> I am not familiar with RDMA, but from the trace we have done so far,
> it is highly related with iser driver.
Do you think it is fair to say that the iSER/block integration is
causing corruption by using un-aligned buffers?
Thanks,
Steve
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Rust <srust@blockbridge.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Rob Townley <rob.townley@gmail.com>,
Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-scsi@vger.kernel.org, martin.petersen@oracle.com,
target-devel@vger.kernel.org, Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Sagi Grimberg <sagi@grimberg.me>,
Max Gurtovoy <maxg@mellanox.com>
Subject: Re: Data corruption in kernel 5.1+ with iSER attached ramdisk
Date: Thu, 05 Dec 2019 02:28:43 +0000 [thread overview]
Message-ID: <CAAFE1bcwcdVuzAG5+x1UNcTaa22bf0tOaT=QOWrTup98sFXxuQ@mail.gmail.com> (raw)
In-Reply-To: <20191204230225.GA26189@ming.t460p>
Hi Ming,
Thanks for all your help and insight. I really appreciate it.
> > Presumably non-brd devices, ie: real scsi devices work for these test
> > cases because they accept un-aligned buffers?
>
> Right, not every driver supports such un-aligned buffer.
Can you please clarify: does the block layer require that it is called
with 512-byte aligned buffers? If that is the case, would it make
sense for the block interface (bio_add_page() or other) to reject
buffers that are not aligned?
It seems that passing these buffers on to underlying drivers that
don't support un-aligned buffers can result in silent data corruption.
Perhaps it would be better to fail the I/O up front. This would also
help future proof the block interface when changes/new target drivers
are added.
I'm also curious how these same unaligned buffers from iSER made it to
brd and were written successfully in the pre "multi-page bvec" world.
(Just trying to understand, if you have any thoughts, as this same
test case worked fine in 4.14+ until 5.1)
> I am not familiar with RDMA, but from the trace we have done so far,
> it is highly related with iser driver.
Do you think it is fair to say that the iSER/block integration is
causing corruption by using un-aligned buffers?
Thanks,
Steve
next prev parent reply other threads:[~2019-12-05 2:28 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAAFE1bd9wuuobpe4VK7Ty175j7mWT+kRmHCNhVD+6R8MWEAqmw@mail.gmail.com>
2019-11-28 1:57 ` Data corruption in kernel 5.1+ with iSER attached ramdisk Ming Lei
2019-11-28 1:57 ` Ming Lei
[not found] ` <CA+VdTb_-CGaPjKUQteKVFSGqDz-5o-tuRRkJYqt8B9iOQypiwQ@mail.gmail.com>
2019-11-28 2:58 ` Ming Lei
2019-11-28 2:58 ` Ming Lei
[not found] ` <CAAFE1bfsXsKGyw7SU_z4NanT+wmtuJT=XejBYbHHMCDQwm73sw@mail.gmail.com>
2019-11-28 4:25 ` Stephen Rust
2019-11-28 4:25 ` Stephen Rust
2019-11-28 5:51 ` Rob Townley
2019-11-28 5:51 ` Rob Townley
2019-11-28 9:12 ` Ming Lei
2019-11-28 9:12 ` Ming Lei
2019-12-02 18:42 ` Stephen Rust
2019-12-02 18:42 ` Stephen Rust
2019-12-03 0:58 ` Ming Lei
2019-12-03 0:58 ` Ming Lei
2019-12-03 3:04 ` Stephen Rust
2019-12-03 3:04 ` Stephen Rust
2019-12-03 3:14 ` Ming Lei
2019-12-03 3:14 ` Ming Lei
2019-12-03 3:26 ` Stephen Rust
2019-12-03 3:26 ` Stephen Rust
2019-12-03 3:50 ` Stephen Rust
2019-12-03 3:50 ` Stephen Rust
2019-12-03 12:45 ` Ming Lei
2019-12-03 12:45 ` Ming Lei
2019-12-03 19:56 ` Stephen Rust
2019-12-03 19:56 ` Stephen Rust
2019-12-04 1:05 ` Ming Lei
2019-12-04 1:05 ` Ming Lei
2019-12-04 17:23 ` Stephen Rust
2019-12-04 17:23 ` Stephen Rust
2019-12-04 23:02 ` Ming Lei
2019-12-04 23:02 ` Ming Lei
2019-12-05 0:16 ` Bart Van Assche
2019-12-05 0:16 ` Bart Van Assche
2019-12-05 14:44 ` Stephen Rust
2019-12-05 14:44 ` Stephen Rust
2019-12-05 2:28 ` Stephen Rust [this message]
2019-12-05 2:28 ` Stephen Rust
2019-12-05 3:05 ` Ming Lei
2019-12-05 3:05 ` Ming Lei
2019-12-05 9:17 ` Sagi Grimberg
2019-12-05 9:17 ` Sagi Grimberg
2019-12-05 14:36 ` Stephen Rust
2019-12-05 14:36 ` Stephen Rust
[not found] ` <CAAFE1beqFBQS_zVYEXFTD2qu8PAF9hBSW4j1k9ZD6MhU_gWg5Q@mail.gmail.com>
2020-03-25 0:15 ` Sagi Grimberg
2020-03-25 0:15 ` Sagi Grimberg
2020-03-30 17:08 ` Stephen Rust
2020-03-30 17:08 ` Stephen Rust
2020-03-31 1:07 ` Sagi Grimberg
2020-03-31 1:07 ` Sagi Grimberg
2020-04-01 0:38 ` Sagi Grimberg
2020-04-01 0:38 ` Sagi Grimberg
2020-04-02 20:03 ` Stephen Rust
2020-04-02 20:03 ` Stephen Rust
2020-04-02 22:16 ` Sagi Grimberg
2020-04-02 22:16 ` Sagi Grimberg
2019-12-04 2:39 ` Ming Lei
2019-12-04 2:39 ` Ming Lei
2019-12-03 4:15 ` Ming Lei
2019-12-03 4:15 ` Ming Lei
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