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Date: Sat, 20 Jan 2024 14:43:21 +0100
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Subject: Re: [PATCH v2] mm: align larger anonymous mappings on THP boundaries
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To: Linux kernel regressions list <regressions@lists.linux.dev>
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 <d0a136a0-4a31-46bc-adf4-2db109a61672@kernel.org>
From: "Linux regression tracking #adding (Thorsten Leemhuis)"
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On 16.01.24 12:53, Jiri Slaby wrote:

> On 09. 08. 22, 20:24, Rik van Riel wrote:
>> Align larger anonymous memory mappings on THP boundaries by
>> going through thp_get_unmapped_area if THPs are enabled for
>> the current process.
>>
>> With this patch, larger anonymous mappings are now THP aligned.
>> When a malloc library allocates a 2MB or larger arena, that
>> arena can now be mapped with THPs right from the start, which
>> can result in better TLB hit rates and execution time.
> 
> This appears to break 32bit processes on x86_64 (at least). In
> particular, 32bit kernel or firefox builds in our build system.
> 
> Reverting this on top of 6.7 makes it work again.
> 
> Downstream report:
>  https://bugzilla.suse.com/show_bug.cgi?id=1218841
> [...]
#regzbot ^introduced efa7df3e3bb5
#regzbot title mm: huge_memory: 32 bit systems or compat
userspace broke
#regzbot link: https://bugzilla.suse.com/show_bug.cgi?id=1218841
#regzbot fix: mm: huge_memory: don't force huge page alignment on 32 bit
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
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