linux-kernel - Re: [PATCH] x86/mm: Fix paging-structure cache flush on kernel table freeing

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Message-ID: <aa5f8dbbb5865e7eeb64628beef24fe05d161855.camel@surriel.com>
Date: Thu, 29 May 2025 12:35:23 -0400
From: Rik van Riel <riel@...riel.com>
To: Jann Horn <jannh@...gle.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
  Andy Lutomirski	 <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>
Cc: Toshi Kani <toshi.kani@....com>, linux-kernel@...r.kernel.org, 
	stable@...r.kernel.org
Subject: Re: [PATCH] x86/mm: Fix paging-structure cache flush on kernel
 table freeing

On Wed, 2025-05-28 at 22:30 +0200, Jann Horn wrote:
> 
> Note that since I'm not touching invlpgb_kernel_range_flush() or
> invlpgb_flush_addr_nosync() in this patch, the flush on PMD table
> deletion
> with INVLPGB might be a bit slow due to using PTE_STRIDE instead of
> PMD_STRIDE. I don't think that matters.
> 
Agreed that this is probably fine.

The performance sensitive kernel flushes mostly seem
to be small, related to static key toggling, etc

> Cc: stable@...r.kernel.org
> Fixes: 28ee90fe6048 ("x86/mm: implement free pmd/pte page
> interfaces")
> Signed-off-by: Jann Horn <jannh@...gle.com>

Reviewed-by: Rik van Riel <riel@...riel.com>

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