Re: [PATCH] coredump: get machine check errors early rather than during iov_iter

From: Jens Axboe <axboe@kernel.dk>
To: Christian Brauner <brauner@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Tong Tiangen <tongtiangen@huawei.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	wangkefeng.wang@huawei.com, Guohanjun <guohanjun@huawei.com>,
	David Howells <dhowells@redhat.com>, Al Viro <viro@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] coredump: get machine check errors early rather than during iov_iter
Date: Tue, 5 Mar 2024 09:39:39 -0700	[thread overview]
Message-ID: <db1a16d1-a4c2-4c47-9a84-65e174123078@kernel.dk> (raw)
In-Reply-To: <20240305-staatenlos-vergolden-5c67aef6e2bd@brauner>

On 3/5/24 9:33 AM, Christian Brauner wrote:
> On Tue, 05 Mar 2024 21:33:36 +0800, Tong Tiangen wrote:
>> The commit f1982740f5e7 ("iov_iter: Convert iterate*() to inline funcs")
>> leads to deadloop in generic_perform_write()[1], due to return value of
>> copy_page_from_iter_atomic() changed from non-zero value to zero.
>>
>> The code logic of the I/O performance-critical path of the iov_iter is
>> mixed with machine check[2], actually, there's no need to complicate it,
>> a more appropriate method is to get the error as early as possible in
>> the coredump process instead of during the I/O process. In addition,
>> the iov_iter performance-critical path can have clean logic.
>>
>> [...]
> 
> I'll send this together with two other fixes we have pending.

For what it's worth, checking the two patches, it's basically the one
that Linus sent. I think it should have a From: based on that, and I
also do not see Linus actually signing off on the patch, though that
has been added to this one.

Would probably be sane to get this one resent before applying, properly
done.

Missed that in the first look...

-- 
Jens Axboe