From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
To: David Hildenbrand <david@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andreas Gruenbacher <agruenba@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-s390 <linux-s390@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-btrfs <linux-btrfs@vger.kernel.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Jason Gunthorpe <jgg@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
Heiko Carstens <hca@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>
Subject: Re: Buffered I/O broken on s390x with page faults disabled (gfs2)
Date: Tue, 8 Mar 2022 15:14:43 +0100 [thread overview]
Message-ID: <20220308151443.6be164cf@thinkpad> (raw)
In-Reply-To: <da799fa7-b6c6-eb70-27e4-0c5d8592bd34@redhat.com>
On Tue, 8 Mar 2022 14:32:25 +0100
David Hildenbrand <david@redhat.com> wrote:
[...]
>
> > - using set_pte_at() here seems a bit dangerous, as I'm not sure if this will
> > always only operate on invalid PTEs. Using it on active valid PTEs could
> > result in TLB issues because of missing flush. Also not sure about kvm impact.
> > Using ptep_set_access_flags() seems safer, again similar to touch_pmd() and
> > also cow_user_page().
>
> Yeah, I sticked to what follow_pfn_pte() does for simplicity for now.
Uh oh, that set_pte_at() in follow_pfn_pte() also looks dangerous, at least
I do not spontaneously see that it would only be used for invalid / pte_none()
PTEs. But that is a totally different story, and maybe (hopefully) not
affecting s390 until we have proper DAX support...
next prev parent reply other threads:[~2022-03-08 14:15 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-07 22:52 Buffered I/O broken on s390x with page faults disabled (gfs2) Andreas Gruenbacher
2022-03-07 23:18 ` Linus Torvalds
2022-03-08 8:21 ` David Hildenbrand
2022-03-08 8:37 ` David Hildenbrand
2022-03-08 12:11 ` David Hildenbrand
2022-03-08 12:24 ` David Hildenbrand
2022-03-08 13:20 ` Gerald Schaefer
2022-03-08 13:32 ` David Hildenbrand
2022-03-08 14:14 ` Gerald Schaefer [this message]
2022-03-08 17:23 ` David Hildenbrand
2022-03-08 17:26 ` Linus Torvalds
2022-03-08 17:40 ` Linus Torvalds
2022-03-08 19:27 ` Linus Torvalds
2022-03-08 20:03 ` Linus Torvalds
2022-03-08 23:24 ` Andreas Gruenbacher
2022-03-09 0:22 ` Linus Torvalds
2022-03-09 18:42 ` Andreas Gruenbacher
2022-03-09 19:08 ` Linus Torvalds
2022-03-09 20:57 ` Andreas Gruenbacher
2022-03-09 21:08 ` Andreas Gruenbacher
2022-03-10 12:13 ` Filipe Manana
2022-03-09 19:21 ` Linus Torvalds
2022-03-09 19:35 ` Andreas Gruenbacher
2022-03-09 20:18 ` Linus Torvalds
2022-03-09 20:36 ` Andreas Gruenbacher
2022-03-09 20:48 ` Linus Torvalds
2022-03-09 20:54 ` Linus Torvalds
2022-03-10 17:13 ` David Hildenbrand
2022-03-10 18:00 ` Andreas Gruenbacher
2022-03-10 18:35 ` Linus Torvalds
2022-03-10 18:38 ` David Hildenbrand
2022-03-10 18:47 ` Andreas Gruenbacher
2022-03-10 19:22 ` Linus Torvalds
2022-03-10 19:56 ` Linus Torvalds
2022-03-10 20:23 ` Andreas Gruenbacher
2022-03-08 17:47 ` David Hildenbrand
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