From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E8DB233136 for ; Mon, 17 Nov 2025 01:33:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763343222; cv=none; b=iTHEX9IK+DhXttAI3R3SU8rHusaOU/DwSDXr2Kjz6cTV78NG27SkPFEID4Hmw7NCWLXh+gcy1NOogV/7z+2b4GYBA6HUXt+VRp+FVkM80GBOWQZ0YgVzEBQZcASm8ix5xuB1IOpMWQ+GTLkWcrgz22YBA/dY1kUAetVzc8FdEkU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763343222; c=relaxed/simple; bh=sWPL2cAZs5FMmBzHbaeMFCX5x4oGNhL/IMH4GuNJiKU=; h=Date:To:From:Subject:Message-Id; b=BbqGAu7TeYv016tkE8ibhaIKvGYFEMuABpkKCb1i1VMJgXJ2knuOz1ZpP5aUTkiN+PLUEkThmwfGdTfuufU/GWiBvPMZqTafDey3H5l1wY8J/kc62w/37LHLprUrcjWcIw1DZTtt17TMAy1cH4NRwXhZpJDa8e5hGDwgzNaXtW4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=VljnwPa7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="VljnwPa7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 665CEC4CEF1; Mon, 17 Nov 2025 01:33:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1763343222; bh=sWPL2cAZs5FMmBzHbaeMFCX5x4oGNhL/IMH4GuNJiKU=; h=Date:To:From:Subject:From; b=VljnwPa7UOJznWxmv1e+kyVGxFF191zl1ArIcVjvJBjW333GG1auL9hRMFyobpLlx KW9NjAJquoTeKNuXrZfHM5Gi+I3zA3MzTKl2rr1gvPQHmNjpICtmsR7CVfidpbEdDy LxsOgEG4OjkUX5JHdVIPxLTd2q8KEhymGM38eqZM= Date: Sun, 16 Nov 2025 17:33:41 -0800 To: mm-commits@vger.kernel.org,yi1.lai@intel.com,willy@infradead.org,will@kernel.org,vinicius.gomes@intel.com,vbabka@suse.cz,vasant.hegde@amd.com,urezki@gmail.com,tglx@linutronix.de,rppt@kernel.org,robin.murphy@arm.com,peterz@infradead.org,mingo@redhat.com,mhocko@kernel.org,luto@kernel.org,lorenzo.stoakes@oracle.com,liam.howlett@oracle.com,kevin.tian@intel.com,joro@8bytes.org,jgg@nvidia.com,jean-philippe@linaro.org,jannh@google.com,david@redhat.com,bp@alien8.de,baolu.lu@linux.intel.com,apopple@nvidia.com,dave.hansen@linux.intel.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-introduce-deferred-freeing-for-kernel-page-tables.patch removed from -mm tree Message-Id: <20251117013342.665CEC4CEF1@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: introduce deferred freeing for kernel page tables has been removed from the -mm tree. Its filename was mm-introduce-deferred-freeing-for-kernel-page-tables.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Dave Hansen Subject: mm: introduce deferred freeing for kernel page tables Date: Wed, 22 Oct 2025 16:26:33 +0800 This introduces a conditional asynchronous mechanism, enabled by CONFIG_ASYNC_KERNEL_PGTABLE_FREE. When enabled, this mechanism defers the freeing of pages that are used as page tables for kernel address mappings. These pages are now queued to a work struct instead of being freed immediately. This deferred freeing allows for batch-freeing of page tables, providing a safe context for performing a single expensive operation (TLB flush) for a batch of kernel page tables instead of performing that expensive operation for each page table. Link: https://lkml.kernel.org/r/20251022082635.2462433-8-baolu.lu@linux.intel.com Signed-off-by: Dave Hansen Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Acked-by: David Hildenbrand Acked-by: Mike Rapoport (Microsoft) Cc: Alistair Popple Cc: Andy Lutomirski Cc: Borislav Betkov Cc: Ingo Molnar Cc: Jann Horn Cc: Jean-Philippe Brucker Cc: Joerg Roedel Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Peter Zijlstra Cc: Robin Murohy Cc: Thomas Gleinxer Cc: "Uladzislau Rezki (Sony)" Cc: Vasant Hegde Cc: Vinicius Costa Gomes Cc: Vlastimil Babka Cc: Will Deacon Cc: Yi Lai Signed-off-by: Andrew Morton --- include/linux/mm.h | 16 +++++++++++++--- mm/Kconfig | 3 +++ mm/pgtable-generic.c | 37 +++++++++++++++++++++++++++++++++++++ 3 files changed, 53 insertions(+), 3 deletions(-) --- a/include/linux/mm.h~mm-introduce-deferred-freeing-for-kernel-page-tables +++ a/include/linux/mm.h @@ -3053,6 +3053,14 @@ static inline void __pagetable_free(stru __free_pages(page, compound_order(page)); } +#ifdef CONFIG_ASYNC_KERNEL_PGTABLE_FREE +void pagetable_free_kernel(struct ptdesc *pt); +#else +static inline void pagetable_free_kernel(struct ptdesc *pt) +{ + __pagetable_free(pt); +} +#endif /** * pagetable_free - Free pagetables * @pt: The page table descriptor @@ -3062,10 +3070,12 @@ static inline void __pagetable_free(stru */ static inline void pagetable_free(struct ptdesc *pt) { - if (ptdesc_test_kernel(pt)) + if (ptdesc_test_kernel(pt)) { ptdesc_clear_kernel(pt); - - __pagetable_free(pt); + pagetable_free_kernel(pt); + } else { + __pagetable_free(pt); + } } #if defined(CONFIG_SPLIT_PTE_PTLOCKS) --- a/mm/Kconfig~mm-introduce-deferred-freeing-for-kernel-page-tables +++ a/mm/Kconfig @@ -906,6 +906,9 @@ config HAVE_GIGANTIC_FOLIOS def_bool (HUGETLB_PAGE && ARCH_HAS_GIGANTIC_PAGE) || \ (ZONE_DEVICE && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) +config ASYNC_KERNEL_PGTABLE_FREE + def_bool n + # TODO: Allow to be enabled without THP config ARCH_SUPPORTS_HUGE_PFNMAP def_bool n --- a/mm/pgtable-generic.c~mm-introduce-deferred-freeing-for-kernel-page-tables +++ a/mm/pgtable-generic.c @@ -406,3 +406,40 @@ again: pte_unmap_unlock(pte, ptl); goto again; } + +#ifdef CONFIG_ASYNC_KERNEL_PGTABLE_FREE +static void kernel_pgtable_work_func(struct work_struct *work); + +static struct { + struct list_head list; + /* protect above ptdesc lists */ + spinlock_t lock; + struct work_struct work; +} kernel_pgtable_work = { + .list = LIST_HEAD_INIT(kernel_pgtable_work.list), + .lock = __SPIN_LOCK_UNLOCKED(kernel_pgtable_work.lock), + .work = __WORK_INITIALIZER(kernel_pgtable_work.work, kernel_pgtable_work_func), +}; + +static void kernel_pgtable_work_func(struct work_struct *work) +{ + struct ptdesc *pt, *next; + LIST_HEAD(page_list); + + spin_lock(&kernel_pgtable_work.lock); + list_splice_tail_init(&kernel_pgtable_work.list, &page_list); + spin_unlock(&kernel_pgtable_work.lock); + + list_for_each_entry_safe(pt, next, &page_list, pt_list) + __pagetable_free(pt); +} + +void pagetable_free_kernel(struct ptdesc *pt) +{ + spin_lock(&kernel_pgtable_work.lock); + list_add(&pt->pt_list, &kernel_pgtable_work.list); + spin_unlock(&kernel_pgtable_work.lock); + + schedule_work(&kernel_pgtable_work.work); +} +#endif _ Patches currently in -mm which might be from dave.hansen@linux.intel.com are