+ um-mm-enable-mmu_gather_rcu_table_free.patch added to mm-new branch

+ um-mm-enable-mmu_gather_rcu_table_free.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: um: mm: enable MMU_GATHER_RCU_TABLE_FREE
has been added to the -mm mm-new branch.  Its filename is
     um-mm-enable-mmu_gather_rcu_table_free.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/um-mm-enable-mmu_gather_rcu_table_free.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

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------------------------------------------------------
From: Qi Zheng <zhengqi.arch@bytedance.com>
Subject: um: mm: enable MMU_GATHER_RCU_TABLE_FREE
Date: Wed, 17 Dec 2025 17:45:47 +0800

On a 64-bit system, madvise(MADV_DONTNEED) may cause a large number of
empty PTE page table pages (such as 100GB+).  To resolve this problem,
first enable MMU_GATHER_RCU_TABLE_FREE to prepare for enabling the
PT_RECLAIM feature, which resolves this problem.

Link: https://lkml.kernel.org/r/d8f1206ed75231c66a3269149dbefe68c2dc1ddc.1765963770.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/um/Kconfig |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/um/Kconfig~um-mm-enable-mmu_gather_rcu_table_free
+++ a/arch/um/Kconfig
@@ -42,6 +42,7 @@ config UML
 	select HAVE_SYSCALL_TRACEPOINTS
 	select THREAD_INFO_IN_TASK
 	select SPARSE_IRQ
+	select MMU_GATHER_RCU_TABLE_FREE
 
 config MMU
 	bool
_

Patches currently in -mm which might be from zhengqi.arch@bytedance.com are

mm-change-mm-pt_reclaimc-to-use-asm-tlbh-instead-of-asm-generic-tlbh.patch
alpha-mm-enable-mmu_gather_rcu_table_free.patch
loongarch-mm-enable-mmu_gather_rcu_table_free.patch
mips-mm-enable-mmu_gather_rcu_table_free.patch
parisc-mm-enable-mmu_gather_rcu_table_free.patch
um-mm-enable-mmu_gather_rcu_table_free.patch
mm-make-pt_reclaim-depends-on-mmu_gather_rcu_table_free.patch