From: Mike Kravetz <mike.kravetz@oracle.com>
To: Miklos Szeredi <miklos@szeredi.hu>, Amir Goldstein <amir73il@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>, Linux MM <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
overlayfs <linux-unionfs@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Colin Walters <walters@verbum.org>,
Andrew Morton <akpm@linux-foundation.org>,
syzbot <syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify hugetlbfs files
Date: Mon, 15 Jun 2020 10:48:11 -0700 [thread overview]
Message-ID: <33cbc2b6-a37a-8bd1-d896-f4318a61b8ca@oracle.com> (raw)
In-Reply-To: <CAJfpegv28Z2aECcb+Yfqum54zfwV=k1G1n_o3o6O-QTWOy3T4Q@mail.gmail.com>
On 6/15/20 1:24 AM, Miklos Szeredi wrote:
> On Sat, Jun 13, 2020 at 8:53 AM Amir Goldstein <amir73il@gmail.com> wrote:
>
>>> I also looked at normal filesystem lower and hugetlbfs upper. Yes, overlayfs
>>> allows this. This is somewhat 'interesting' as write() is not supported in
>>> hugetlbfs. Writing to files in the overlay actually ended up writing to
>>> files in the lower filesystem. That seems wrong, but overlayfs is new to me.
>
> Yes, this very definitely should not happen.
>
>> I am not sure how that happened, but I think that ovl_open_realfile()
>> needs to fixup f_mode flags FMODE_CAN_WRITE | FMODE_CAN_READ
>> after open_with_fake_path().
>
> Okay, but how did the write actually get to the lower layer?
>
> I failed to reproduce this. Mike, how did you trigger this?
My apologies!!!
I reviewed my testing and found that it was incorrectly writing to the
lower filesystem. Writing to any file in the union will fail.
--
Mike Kravetz
next prev parent reply other threads:[~2020-06-15 17:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-12 0:46 [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify hugetlbfs files Mike Kravetz
2020-06-12 0:46 ` [PATCH v4 2/2] ovl: call underlying get_unmapped_area() routine. propogate FMODE_HUGETLBFS Mike Kravetz
2020-06-14 12:50 ` Amir Goldstein
2020-06-12 1:53 ` [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify hugetlbfs files Matthew Wilcox
2020-06-12 1:58 ` Al Viro
2020-06-12 21:51 ` Mike Kravetz
2020-06-13 6:53 ` Amir Goldstein
2020-06-13 14:38 ` Matthew Wilcox
2020-06-13 19:12 ` Mike Kravetz
2020-06-15 7:53 ` Miklos Szeredi
2020-06-15 10:05 ` Amir Goldstein
2020-06-15 13:01 ` Miklos Szeredi
2020-06-15 23:45 ` Mike Kravetz
2020-06-16 9:01 ` Miklos Szeredi
2020-06-15 8:24 ` Miklos Szeredi
2020-06-15 17:48 ` Mike Kravetz [this message]
2020-06-12 6:28 ` [RFC PATCH] hugetlb: hugetlbfs_file_operations can be static kernel test robot
2020-06-13 14:19 ` [hugetlb] 5156c6c1b9: INFO:trying_to_register_non-static_key kernel test robot
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