From: Ming Lin <minggr@gmail.com>
To: Hugh Dickins <hughd@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Simon Ser <contact@emersion.fr>
Cc: Peter Xu <peterx@redhat.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Will Deacon <will@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
David Herrmann <dh.herrmann@gmail.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Greg Kroah-Hartman <greg@kroah.com>,
"tytso@mit.edu" <tytso@mit.edu>
Subject: Re: Sealed memfd & no-fault mmap
Date: Mon, 31 May 2021 14:13:28 -0700 [thread overview]
Message-ID: <e7454046-c071-888d-f673-276f9c24d9d3@gmail.com> (raw)
In-Reply-To: <36fc2485-11f1-5252-904d-f26b63a6cd58@gmail.com>
On 5/29/2021 4:36 PM, Ming Lin wrote:
> On 5/29/2021 1:15 PM, Hugh Dickins wrote:
>
>>
>> I believe the correct behaviour would be to unmap the nofault page
>> then, allowing the proper page to be faulted in after. That is
>> certainly doable (the old mm/filemap_xip.c used to do so), but might
>> get into some awkward race territory, with filesystem dependence
>> (reminiscent of hole punch, in reverse). shmem could operate that
>> way, and be the better for it: but I wouldn't want to add that,
>> without also cleaning away all the shmem_recalc_inode() stuff.
OK, I borrowed code from filemap_xip.c and implemented this behavior.
Simon,
Before I send out the patches for review, would you mind have a quick test?
https://github.com/minggr/linux, branch shmem_no_sigbus
In Wayland compositors, you only need to pass in MAP_NOSIGBUS in mmap().
For example,
//fd should be received from Wayland compositors client
#define MAP_NOSIGBUS 0x200000
addr = mmap(NULL, size, PROT_READ, MAP_SHARED|MAP_NOSIGBUS, fd, offset)
Thanks,
Ming
next prev parent reply other threads:[~2021-05-31 21:13 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 8:24 Sealed memfd & no-fault mmap Simon Ser
2021-04-27 16:51 ` Linus Torvalds
2021-04-29 15:48 ` Kirill A. Shutemov
2021-04-29 18:38 ` Peter Xu
2021-05-04 9:29 ` Simon Ser
2021-05-04 16:08 ` Linus Torvalds
2021-05-05 10:21 ` Simon Ser
2021-05-05 18:42 ` Linus Torvalds
2021-05-28 17:07 ` Lin, Ming
2021-05-29 1:03 ` Linus Torvalds
2021-05-29 7:31 ` Lin, Ming
2021-05-29 15:44 ` Linus Torvalds
2021-05-29 20:15 ` Hugh Dickins
2021-05-29 23:36 ` Ming Lin
2021-05-31 21:13 ` Ming Lin [this message]
2021-06-01 6:24 ` Linus Torvalds
2021-06-01 7:08 ` Ming Lin
2021-06-03 13:01 ` Simon Ser
2021-06-03 20:07 ` Ming Lin
2021-06-03 20:49 ` Simon Ser
2021-06-03 13:14 ` Simon Ser
2021-06-03 13:57 ` Matthew Wilcox
2021-06-03 14:48 ` Simon Ser
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