Re: [PATCH v5] MIPS: mm: kmalloc tlb_vpn array to avoid stack overflow

[Thomas Bogendoerfer <tsbogend@alpha.franken.de>]

On Fri, Nov 28, 2025 at 04:53:46PM +0000, Maciej W. Rozycki wrote:
> From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> 
> Owing to Config4.MMUSizeExt and VTLB/FTLB MMU features later MIPSr2+ 
> cores can have more than 64 TLB entries.  Therefore allocate an array 
> for uniquification instead of placing too small an array on the stack.
> 
> Fixes: 35ad7e181541 ("MIPS: mm: tlb-r4k: Uniquify TLB entries on init")
> Co-developed-by: Maciej W. Rozycki <macro@orcam.me.uk>
> Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: stable@vger.kernel.org # v6.17+: 9f048fa48740: MIPS: mm: Prevent a TLB shutdown on initial uniquification
> Cc: stable@vger.kernel.org # v6.17+
> ---
>  Verified with Malta/74Kf and Malta/interAptiv for initial and secondary 
> CPU bootstrap.  The PM path hasn't been covered, but is expected to be 
> the same as secondary CPU bootstrap.
> 
>  NB Malta/interAptiv has issues later on in SMP boot (boots fine UP) and 
> hangs with repeated:
> 
> irq 23: nobody cared (try booting with the "irqpoll" option)
> CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.18.0-rc1-dirty #2 NONE
> 
> messages (for the CP0 timer interrupt AFAICT; GIC timer is supposed to 
> be used instead).  This will have to be bisected.
> 
> Changes from v4:
> 
> - Mark `r4k_tlb_uniquify' `__ref' so as to silence `modpost'.
> 
> Changes from v3:
> 
> - Rearrange tags including stable backport ones so as to pick the original 
>   change together with this fix only.
> 
> Changes from v2:
> 
> - Use the bootmem allocator for early calls (CPU #0 bootstrap).
> 
> - Update the change description; mark for stable backporting.
> ---
>  arch/mips/mm/tlb-r4k.c |   18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)

applied to mips-fixes.

Thomas.

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