linux-kernel - Re: [PATCH] bcachefs: fix alignment of VMA for memory mapped files on THP

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Date: Fri, 21 Jun 2024 09:11:52 +0800
From: Youling Tang <youling.tang@...ux.dev>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: linux-bcachefs@...r.kernel.org, linux-kernel@...r.kernel.org,
 Youling Tang <tangyouling@...inos.cn>
Subject: Re: [PATCH] bcachefs: fix alignment of VMA for memory mapped files on
 THP

Hi, Kent

Sorry to bother you, BTW, are the following patches still needed?

https://lore.kernel.org/linux-bcachefs/20240604084610.94558-1-youling.tang@linux.dev/
https://lore.kernel.org/linux-bcachefs/20240418083103.66703-1-youling.tang@linux.dev/
https://lore.kernel.org/linux-bcachefs/20240418005055.45482-1-youling.tang@linux.dev/

Thanks,
Youling.

On 20/06/2024 20:51, Kent Overstreet wrote:
> On Thu, Jun 20, 2024 at 09:22:42AM +0800, Youling Tang wrote:
>> From: Youling Tang <tangyouling@...inos.cn>
>>
>> With CONFIG_READ_ONLY_THP_FOR_FS, the Linux kernel supports using THPs
>> for read-only mmapped files, such as shared libraries. However, the
>> kernel makes no attempt to actually align those mappings on 2MB
>> boundaries, which makes it impossible to use those THPs most of the
>> time. This issue applies to general file mapping THP as well as
>> existing setups using CONFIG_READ_ONLY_THP_FOR_FS. This is easily
>> fixed by using thp_get_unmapped_area for the unmapped_area function
>> in bcachefs, which is what ext2, ext4, fuse, xfs and btrfs all use.
>>
>> Similar to commit b0c582233a85 ("btrfs: fix alignment of VMA for
>> memory mapped files on THP").
>>
>> Signed-off-by: Youling Tang <tangyouling@...inos.cn>
> Thanks - applied