Re: [PATCH v2 10/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sparc32

[sashiko-bot@kernel.org]

> Careful handling is required for sparc32 which implements page tables as
> part of a shared backing page.
> 
> To support this, a custom __tlb_remove_table() function is required, as
> specified by CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE.
> 
> This allows __pte_free_tlb() and __pmd_free_tlb() to specify which page
> table level is being freed, which is transmitted to __tlb_remove_table()
> through setting the lowest bit of the page table to 1 for a PMD and 0 for a
> PTE (the page tables are 256-byte aligned so this is safe to do).
> 
> Next, since the page table freeing is done via RCU callback, and thus might
> be executed in softirq context, update the spin locks to IRQ save/restore.
> 
> Then, in __tlb_remove_table(), figure out whether to free a PMD page table
> [ ... ]
> This forms part of an overall effort to switch every architecture to this
> mode, and with it complete, means every architecture now supports
> CONFIG_MMU_GATHER_RCU_TABLE_FREE.
> 
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260908-rcu-pagetable-freeing-v2-0-1f60b64e878e@kernel.org?part=10