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Message-ID: <dc4933d0-f865-4da6-90b1-320daf2e4294@kernel.dk>
Date: Tue, 5 Mar 2024 06:58:59 -0700
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Subject: Re: [PATCH] coredump: get machine check errors early rather than
 during iov_iter
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To: Tong Tiangen <tongtiangen@huawei.com>,
 Linus Torvalds <torvalds@linux-foundation.org>,
 David Howells <dhowells@redhat.com>, Al Viro <viro@kernel.org>,
 Alexander Viro <viro@zeniv.linux.org.uk>,
 Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
 Andrew Morton <akpm@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
 wangkefeng.wang@huawei.com, Guohanjun <guohanjun@huawei.com>
References: <20240305133336.3804360-1-tongtiangen@huawei.com>
From: Jens Axboe <axboe@kernel.dk>
In-Reply-To: <20240305133336.3804360-1-tongtiangen@huawei.com>
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On 3/5/24 6:33 AM, 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.

Looks good to me, and I'm a big fan of getting rid of the copy_mc bits
on the generic iov iterator side:

Reviewed-by: Jens Axboe <axboe@kernel.dk>

-- 
Jens Axboe