From: Matthew Wilcox <willy@infradead.org>
To: Jinjiang Tu <tujinjiang@huawei.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Amir Goldstein <amir73il@gmail.com>,
miklos@szeredi.hu, akpm@linux-foundation.org, vbabka@suse.cz,
jannh@google.com, linux-mm@kvack.org,
linux-unionfs@vger.kernel.org, wangkefeng.wang@huawei.com,
sunnanyong@huawei.com, yi.zhang@huawei.com,
Liam Howlett <liam.howlett@oracle.com>
Subject: Re: [PATCH -next] ovl: respect underlying filesystem's get_unmapped_area()
Date: Fri, 6 Dec 2024 13:52:16 +0000 [thread overview]
Message-ID: <Z1MBkH_PeZto3qkC@casper.infradead.org> (raw)
In-Reply-To: <518c881b-8ba0-df0e-16bf-00694c59f5a7@huawei.com>
On Fri, Dec 06, 2024 at 11:35:20AM +0800, Jinjiang Tu wrote:
> When usespace calls mmap syscall, the call trace is as follows:
>
> do_mmap
> __get_unmapped_area
> mmap_region
> mmap_file
> ovl_mmap
>
> __get_unmapped_area() gets the address to mmap at, the file here is an overlayfs file.
> Since ovl_file_operations doesn't defines get_unmapped_area callback, __get_unmapped_area()
> fallbacks to mm_get_unmapped_area_vmflags(), and it doesn't return an address aligned to
> large folio size.
It doesn't need to. large folios can be mapped at any alignment.
The get_unmapped_area overrides are just for efficiency (ie be
able to use PMD mappings when we happen to get a PMD-sized folio).
next prev parent reply other threads:[~2024-12-06 13:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-05 14:30 Jinjiang Tu
2024-12-05 15:04 ` Lorenzo Stoakes
2024-12-05 15:12 ` Amir Goldstein
2024-12-05 15:24 ` Lorenzo Stoakes
2024-12-06 3:35 ` Jinjiang Tu
2024-12-06 13:52 ` Matthew Wilcox [this message]
2024-12-10 17:36 ` Jann Horn
2024-12-06 3:35 ` Jinjiang Tu
2024-12-06 9:25 ` Lorenzo Stoakes
2024-12-06 10:45 ` Kefeng Wang
2024-12-06 11:53 ` Lorenzo Stoakes
2024-12-10 7:09 ` Kefeng Wang
2024-12-06 12:58 ` Amir Goldstein
2024-12-10 7:19 ` Kefeng Wang
2024-12-11 9:43 ` Amir Goldstein
2024-12-11 15:01 ` Kefeng Wang
2024-12-13 1:51 ` Jinjiang Tu
2024-12-13 4:25 ` Matthew Wilcox
2024-12-13 7:49 ` Kefeng Wang
2024-12-13 14:00 ` Matthew Wilcox
2024-12-14 7:58 ` Kefeng Wang
2024-12-05 21:21 ` kernel test robot
2024-12-06 13:58 ` Matthew Wilcox
2024-12-09 6:43 ` Jinjiang Tu
2024-12-09 13:33 ` Matthew Wilcox
2024-12-10 7:13 ` Jinjiang Tu
2024-12-10 17:58 ` Matthew Wilcox
2024-12-11 2:21 ` Zhang Yi
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