From: "Christian König" <christian.koenig@amd.com>
To: Jason Gunthorpe <jgg@ziepe.ca>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org,
linux-media@vger.kernel.org, chris@chris-wilson.co.uk,
airlied@redhat.com, akpm@linux-foundation.org,
sumit.semwal@linaro.org
Subject: Re: [PATCH 1/4] mm: introduce vma_set_file function v2
Date: Fri, 9 Oct 2020 14:15:16 +0200 [thread overview]
Message-ID: <db073cdb-db29-0a3c-4295-4205c6ddfadc@amd.com> (raw)
In-Reply-To: <20201009121220.GM5177@ziepe.ca>
Am 09.10.20 um 14:12 schrieb Jason Gunthorpe:
> On Fri, Oct 09, 2020 at 09:39:00AM +0200, Daniel Vetter wrote:
>> I just noticed this here in the patch because everyone else does not do
>> this. But looking at the mmap_region() code in mmap.c we seem to indeed
>> have this problem for the error path:
>>
>> unmap_and_free_vma:
>> vma->vm_file = NULL;
>> fput(file);
>>
>> Note that the success path does things correctly (a bit above):
>>
>> file = vma->vm_file;
>> out:
>>
>> So it indeed looks like dma-buf is the only one that does this fully
>> correctly. So maybe we should do a follow-up patch to change the
>> mmap_region exit code to pick up whatever vma->vm_file was set instead,
>> and fput that?
> Given that this new vma_set_file() should be the only way to
> manipulate vm_file from the mmap op, I think this reflects a bug in
> mm/mmap.c.. Should be:
>
> unmap_and_free_vma:
> fput(vma->vm_file);
> vma->vm_file = NULL;
>
> Then everything works the way you'd expect without tricky error
> handling
That's what Daniel suggested as well, yes.
Going to craft a separate patch for this.
Thanks,
Christian.
>
> Jason
next prev parent reply other threads:[~2020-10-09 12:15 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 11:23 [PATCH 1/4] mm: introduce vma_set_file function v2 Christian König
2020-10-08 11:23 ` [PATCH 2/4] drm/prime: document that use the page array is deprecated Christian König
2020-10-08 14:09 ` Daniel Vetter
2020-10-08 14:14 ` Daniel Vetter
2020-10-09 7:36 ` Christian König
2020-10-09 7:40 ` Daniel Vetter
2020-10-08 11:23 ` [PATCH 3/4] drm/radeon: stop using pages with drm_prime_sg_to_page_addr_arrays Christian König
2020-10-08 11:23 ` [PATCH 4/4] drm/amdgpu: " Christian König
2020-10-08 11:39 ` [PATCH 1/4] mm: introduce vma_set_file function v2 Matthew Wilcox
2020-10-08 12:06 ` Christian König
2020-10-08 14:12 ` Daniel Vetter
2020-10-09 7:16 ` Christian König
2020-10-09 7:39 ` Daniel Vetter
2020-10-09 12:12 ` Jason Gunthorpe
2020-10-09 12:15 ` Christian König [this message]
2020-10-08 15:35 ` kernel test robot
2020-10-08 16:19 ` kernel test robot
2020-10-08 21:49 ` John Hubbard
2020-10-09 7:33 ` Christian König
2020-10-09 7:36 ` John Hubbard
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=db073cdb-db29-0a3c-4295-4205c6ddfadc@amd.com \
--to=christian.koenig@amd.com \
--cc=airlied@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=chris@chris-wilson.co.uk \
--cc=dri-devel@lists.freedesktop.org \
--cc=jgg@ziepe.ca \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=sumit.semwal@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).