linux-kernel - Re: [PATCH 5.18 112/181] vmcore: convert copy_oldmem_page() to take an iov

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Message-ID: <YsMisFQdaUZpxroY@casper.infradead.org>
Date:   Mon, 4 Jul 2022 18:26:08 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Alexander Gordeev <agordeev@...ux.ibm.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Baoquan He <bhe@...hat.com>, Christoph Hellwig <hch@....de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>,
        Vasily Gorbik <gor@...ux.ibm.com>
Subject: Re: [PATCH 5.18 112/181] vmcore: convert copy_oldmem_page() to take
 an iov_iter

On Tue, Jun 28, 2022 at 10:29:04AM +0200, Alexander Gordeev wrote:
> On Tue, Jun 28, 2022 at 09:09:05AM +0200, Greg Kroah-Hartman wrote:
> > > This one breaks s390. You would also need to apply the following two commits:
> > > 
> > > cc02e6e21aa5 ("s390/crash: add missing iterator advance in copy_oldmem_page()")
> > > af2debd58bd7 ("s390/crash: make copy_oldmem_page() return number of bytes copied")
> > 
> > Both of them are also in the 5.18-rc queue here, right?
> 
> Yes, these are:
> 
> 	[PATCH 5.18 113/181] s390/crash: add missing iterator advance in copy_oldmem_page() Greg Kroah-Hartman

It's generally considered polite to cc the original author when you
fix one of their patches.  I wasn't aware of this patch.

While the code change looks right, the commit message is wrong;
copy_oldmem_user() and copy_oldmem_kernel() need to GO AWAY.  You
need to be more like the other architectures and end up calling
copy_to_iter().  I have no idea what this memcpy_hsa_kernel()
and memcpy_hsa_user() are all about, but I was hoping that somebody
from the s390 team would react to:

    s390 needs more work to pass the iov_iter down further, or refactor, but
    I'd be more comfortable if someone who can test on s390 did that work.

Maybe you'll do it.