linux-kernel - Re: [PATCH] coredump: get machine check errors early rather than during iov

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Message-ID: <dc4933d0-f865-4da6-90b1-320daf2e4294@kernel.dk>
Date: Tue, 5 Mar 2024 06:58:59 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Tong Tiangen <tongtiangen@...wei.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 David Howells <dhowells@...hat.com>, Al Viro <viro@...nel.org>,
 Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 wangkefeng.wang@...wei.com, Guohanjun <guohanjun@...wei.com>
Subject: Re: [PATCH] coredump: get machine check errors early rather than
 during iov_iter

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@...nel.dk>

-- 
Jens Axboe