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 1EFBFC2FB for ; Mon, 12 May 2025 00:51:23 +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=1747011083; cv=none; b=YdDR9ZSdkN2IvDoAbHX5kajHO3a14giyCgx5O28SBG6VJ+9nbCkUwciEG4pTNb3Tco1uAXSrNs4tOBy236od8b0r16bZWTBz/RuSdNs448N5uHw0udHReJ8/ogU8pUL/SNrHpV/6UxTxSEHjCVBEl37aZtxHR+6Fhywd7/n2xio= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747011083; c=relaxed/simple; bh=1SXlTSf3XzK4E+Ym5G1M77wwhD1r6u9eLFaaHE4DV90=; h=Date:To:From:Subject:Message-Id; b=Ez6nkL+sv9Dx77TA8WeemDLlg/INM+vnbDKzgLvN6NAbF/B3Hkl1yGxRycFs5JJcaBumtqCkrXGrTz6mSP0gl8WK9vFxrZo1wvafQY557Q1CItmLgAXZJNdxxeUHjXYczx3zEgu6R6lCsqQ/VYee6CHWHkDUlAqnPjVOrJYrYLU= 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=Dn7HovYI; 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="Dn7HovYI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9DC5C4CEE4; Mon, 12 May 2025 00:51:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1747011083; bh=1SXlTSf3XzK4E+Ym5G1M77wwhD1r6u9eLFaaHE4DV90=; h=Date:To:From:Subject:From; b=Dn7HovYIUxz3lWI1VAhXfMI1OG8h39PV5zts2cdBLmciZLpwGhpjBwOoBmcTE5r3s tt9qh1wUy94TPdSJtsXvII3VhVhpDTogGRXmnXEXPN5oHjsHp7jZTTl3UbPrqo/ZgM UZMv/L+DxOIddG4oIMzHH6N57nuhYMURunuUBZRM= Date: Sun, 11 May 2025 17:51:22 -0700 To: mm-commits@vger.kernel.org,zhengqi.arch@bytedance.com,yang@os.amperecomputing.com,x86@kernel.org,willy@infradead.org,will@kernel.org,ryan.roberts@arm.com,rppt@kernel.org,peterz@infradead.org,paul.walmsley@sifive.com,palmer@dabbelt.com,mpe@ellerman.id.au,mark.rutland@arm.com,maddy@linux.ibm.com,linus.walleij@linaro.org,geert@linux-m68k.org,davem@davemloft.net,dave.hansen@linux.intel.com,catalin.marinas@arm.com,aou@eecs.berkeley.edu,andreas@gaisler.com,agordeev@linux.ibm.com,kevin.brodsky@arm.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-skip-ptlock_init-for-kernel-pmds.patch removed from -mm tree Message-Id: <20250512005122.E9DC5C4CEE4@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: skip ptlock_init() for kernel PMDs has been removed from the -mm tree. Its filename was mm-skip-ptlock_init-for-kernel-pmds.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: Kevin Brodsky Subject: mm: skip ptlock_init() for kernel PMDs Date: Tue, 8 Apr 2025 10:52:17 +0100 Split page table locks are not used for pgtables associated to init_mm, at any level. pte_alloc_kernel() does not call ptlock_init() as a result. There is however no separate alloc/free functions for kernel PMDs, and pmd_ptlock_init() is called unconditionally. When ALLOC_SPLIT_PTLOCKS is true (e.g. 32-bit architectures or if CONFIG_PREEMPT_RT is selected), this results in unnecessary dynamic memory allocation every time a kernel PMD is allocated. Now that pagetable_pmd_ctor() is passed the associated mm, we can easily remove this overhead by skipping pmd_ptlock_init() if the pgtable is associated to init_mm. No special-casing is needed on the dtor path, as ptlock_free() is already called unconditionally for all levels. (ptlock_free() is a no-op unless a ptlock was allocated for the given PTP.) Link: https://lkml.kernel.org/r/20250408095222.860601-8-kevin.brodsky@arm.com Signed-off-by: Kevin Brodsky Cc: Albert Ou Cc: Andreas Larsson Cc: Catalin Marinas Cc: David S. Miller Cc: Geert Uytterhoeven Cc: Linus Waleij Cc: Madhavan Srinivasan Cc: Mark Rutland Cc: Matthew Wilcox (Oracle) Cc: Michael Ellerman Cc: Mike Rapoport Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Qi Zheng Cc: Ryan Roberts Cc: Will Deacon Cc: Cc: Yang Shi Cc: Dave Hansen Cc: Alexander Gordeev Signed-off-by: Andrew Morton --- include/linux/mm.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/include/linux/mm.h~mm-skip-ptlock_init-for-kernel-pmds +++ a/include/linux/mm.h @@ -3257,7 +3257,7 @@ static inline spinlock_t *pmd_lock(struc static inline bool pagetable_pmd_ctor(struct mm_struct *mm, struct ptdesc *ptdesc) { - if (!pmd_ptlock_init(ptdesc)) + if (mm != &init_mm && !pmd_ptlock_init(ptdesc)) return false; ptdesc_pmd_pts_init(ptdesc); __pagetable_ctor(ptdesc); _ Patches currently in -mm which might be from kevin.brodsky@arm.com are