From: Jason Gunthorpe <jgg@ziepe.ca>
To: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
linux-s390@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>
Subject: Re: [RFC PATCH 0/2] mm/gup: fix gup_fast with dynamic page table folding
Date: Fri, 28 Aug 2020 11:21:37 -0300 [thread overview]
Message-ID: <20200828142137.GX24045@ziepe.ca> (raw)
In-Reply-To: <20200828140314.8556-1-gerald.schaefer@linux.ibm.com>
On Fri, Aug 28, 2020 at 04:03:12PM +0200, Gerald Schaefer wrote:
> Commit 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast
> code") introduced a subtle but severe bug on s390 with gup_fast, due to
> dynamic page table folding.
I think the page walk code in mm/pagewalk.c has similar issues to
GUP. I've been noodling on some patches to add the missing stack
copies to pagewalk.c as they are clearly missing..
It would be good if this could be less GUP specific?
Generically this is about walking the page table without holding the
page table spinlocks using READ_ONCE.
Jason
next prev parent reply other threads:[~2020-08-28 14:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-28 14:03 [RFC PATCH 0/2] mm/gup: fix gup_fast with dynamic page table folding Gerald Schaefer
2020-08-28 14:03 ` [RFC PATCH 1/2] " Gerald Schaefer
2020-08-28 14:03 ` [RFC PATCH 2/2] " Gerald Schaefer
2020-08-28 14:21 ` Jason Gunthorpe [this message]
2020-08-28 15:01 ` [RFC PATCH 0/2] " Gerald Schaefer
2020-08-28 15:20 ` Jason Gunthorpe
2020-08-31 11:53 ` Christian Borntraeger
2020-08-31 19:15 ` Andrew Morton
2020-09-01 17:40 ` Gerald Schaefer
2020-09-01 18:14 ` Jason Gunthorpe
2020-09-01 23:22 ` John Hubbard
2020-09-02 12:24 ` Gerald Schaefer
2020-09-02 15:09 ` Gerald Schaefer
2020-09-02 20:13 ` Jason Gunthorpe
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