linux-kernel - Re: [PATCH] mm/vmalloc: leave lazy MMU mode on PTE mapping error

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Message-ID: <aFlQv4dx7wFU5Cql@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com>
Date: Mon, 23 Jun 2025 15:03:59 +0200
From: Alexander Gordeev <agordeev@...ux.ibm.com>
To: Ryan Roberts <ryan.roberts@....com>
Cc: Dan Carpenter <dan.carpenter@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/vmalloc: leave lazy MMU mode on PTE mapping error

On Mon, Jun 23, 2025 at 01:37:11PM +0100, Ryan Roberts wrote:
> On 23/06/2025 08:57, Alexander Gordeev wrote:
> > Function vmap_pages_pte_range() enters the lazy MMU mode,
> > but fails to leave it in case an error is encountered.
> > 
> > Reported-by: kernel test robot <lkp@...el.com>
> > Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> > Closes: https://lore.kernel.org/r/202506132017.T1l1l6ME-lkp@intel.com/
> > Fixes: 44562c71e2cf ("mm/vmalloc: Enter lazy mmu mode while manipulating vmalloc ptes")
> > Signed-off-by: Alexander Gordeev <agordeev@...ux.ibm.com>
> 
> Ouch, sorry about that! The patch looks good to me so:
> 
> Reviewed-by: Ryan Roberts <ryan.roberts@....com>
> 
> I wonder an aditional Fixes: should be added for Commit 2ba3e6947aed
> ("mm/vmalloc: track which page-table levels were modified") though? That's the
> one that added the "*mask |= PGTBL_PTE_MODIFIED;" which would have also been
> skipped if an error occured before this patch.

Good catch! I think it certainly needs to be reported with Fixes
and I even doubt whether your commit should be mentioned at all?

> Thanks,
> Ryan

Thanks!