From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AA332C531C9 for ; Sat, 25 Jul 2026 17:38:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=QylY0Jj+M9aiGs5V5SL5IjP/iHtiFsye8Zowe/lAKfs=; b=FHkpgbktHtV6X2p5Ng9XuoszZ8 a7wqowrGd8ZMIRDnp99Udwf2R7Zg1sNVZhO6eMZhEjKNmOP4pRRW9IGQQbfkGwwMCeqElmYk5Xabo mFBkB6XAP3oC0PFx5GyWL9llb+jU2McDssCTcQ0JBXD7xFH9UgulR08EkJgsOWP6v/fpwxsZlKvqd y+zJo4vGhbMLFmMbfkuIfopZy2DV4s3bu63WiZdUeHNvfS4dPZC/2Nu2FqcUpGt1AusOT7CiAVZKJ 6FF3tqmVxB/x0/Ax6qNjXXZF7SzZbALdS6QAsQzWj1hnltIZ95sjSaYEudmaT/b1iWk5xI3+G+E/3 09JaDfig==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wngKZ-00000000cCi-1yVH; Sat, 25 Jul 2026 17:38:35 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wngKY-00000000cCa-0h5j for linux-arm-kernel@lists.infradead.org; Sat, 25 Jul 2026 17:38:34 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 1D17243C37; Sat, 25 Jul 2026 17:38:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C003D1F000E9; Sat, 25 Jul 2026 17:38:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785001112; bh=QylY0Jj+M9aiGs5V5SL5IjP/iHtiFsye8Zowe/lAKfs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=hbLGkWpNrMM4k73a7LkMKOLXC3oYWnMbIQUTX9a1AMPyP+ZB2YtDGSKAOO7LnRTqG vBTBVOyCfgkBM0MWbOb/NoVC5YN9xSGoda6NWf0PzmMOT1fw/XOO6vHcoZm2T9Hnp5 55ibAzms1bMqsEcamK0sa477Sp/cRJs/DtF2sButDQG4u1jm7nFthZJfCS76oVES0q WsTkfomIff31rzlYsktIJhBXeK7omGcTHPA60jUlZ+1E5GFmI8FYxCp3658BnzoxL3 TPxHPEdFzInIhLMkWjbdj7ZY/o7vUtkGVxUVFRul5xDUBZdBWJw09bqSEyMu0nLWef YF/1c7ceJP17Q== Date: Sat, 25 Jul 2026 19:38:23 +0200 From: Helge Deller To: John David Anglin , Usama Arif Cc: Helge Deller , Pedro Falcato , Matthew Wilcox , Andrew Morton , David Hildenbrand , Catalin Marinas , Will Deacon , "James E.J. Bottomley" , Madhavan Srinivasan , Michael Ellerman , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jan Kara , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Kevin Brodsky , Muhammad Usama Anjum , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 3/5] mm/parisc: constify ptep_get() argument Message-ID: References: <20260724102017.141532-1-pfalcato@suse.de> <20260724102017.141532-4-pfalcato@suse.de> <0fd713a8-e4ab-4c07-b36e-79dd138b4a86@linux.dev> <253f7ac0-205b-42f1-9fb5-d19eceb581b6@linux.dev> <3e9dece8-4e86-4ce5-bd74-b3ec305f3003@gmx.de> <4606e13f-6827-45d0-b3b8-6bc26358f7ae@bell.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4606e13f-6827-45d0-b3b8-6bc26358f7ae@bell.net> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org * John David Anglin : > On 2026-07-25 12:27 p.m., Helge Deller wrote: > > On 7/24/26 17:48, Usama Arif wrote: > >> > >> > >> On 24/07/2026 16:32, Pedro Falcato wrote: > >>> On Fri, Jul 24, 2026 at 04:03:44PM +0100, Usama Arif wrote: > >>>> > >>>> > >>>> On 24/07/2026 15:14, Matthew Wilcox wrote: > >>>>> On Fri, Jul 24, 2026 at 02:36:59PM +0100, Usama Arif wrote: > >>>>>> > >>>>>> > >>>>>> On 24/07/2026 11:20, Pedro Falcato wrote: > >>>>>>> ptep_get() does not need write access to the PTE. > >>>>>>> > >>>>>>> Signed-off-by: Pedro Falcato > >>>>>>> --- > >>>>>>>   arch/parisc/include/asm/pgtable.h | 2 +- > >>>>>>>   1 file changed, 1 insertion(+), 1 deletion(-) > >>>>>>> > >>>>>> hmm I think you might break build bisectibility if > >>>>>> you separate out the patches, you should squash patch 3 and 4, > >>>>>> with patch 1. > >>>>> > >>>>> I don't see how this breaks bisectability.  Can you elaborate on what > >>>>> you think would break? > >>>> > >>>> Patch 1 does: > >>>> > >>>> -static inline pte_t ptep_get_lockless(pte_t *ptep) > >>>> +static inline pte_t ptep_get_lockless(const pte_t *ptep) > >>>>   { > >>>>       return ptep_get(ptep); > >>>>   } > >>>> > >>>> > >>>> ptep_get() takes a non-const arg till patch 3 for example for parsic. > >>>> I don't think you can pass a const variable to non const function arg? > >>>> > >>>> So parsic won't compile in patch 1 and 2, powerprc wont compile > >>>> for patches 1, 2 and 3.. > >>> > >>> Aha, yes, nice catch! I'll have to rethink that. Maybe squashing the patches > >>> would be the cleanest way forward. > >>> > >> > >> Yes, squashing is the simplest way forward. > >> > >>> FWIW, the vast majority of architectures aren't doing funny things on > >>> ptep_get(). E.g PA-RISC, loongarch only define these so they can use it in > >>> their own asm/pgtable.h. I'd really like to delete these but I can't tell > >>> if they are *actually* required. > >>> > >> > >> Ah maybe there is something in git history on why it was needed? > >> > >> If not, hopefully someone from the arch lists could clarify.. > > I tried to remove ptep_get() and ptep_test_and_clear_young() from > > arch/parisc/include/asm/pgtable.h, but this then triggers compile errors: > > > >  CC      arch/parisc/kernel/asm-offsets.s > > In file included from /home/cvs/parisc/git-kernel/linus-linux-2.6/include/linux/mm.h:31, > >                  from /home/cvs/parisc/git-kernel/linus-linux-2.6/include/linux/pid_namespace.h:7, > >                  from /home/cvs/parisc/git-kernel/linus-linux-2.6/include/linux/ptrace.h:10, > >                  from /home/cvs/parisc/git-kernel/linus-linux-2.6/arch/parisc/kernel/asm-offsets.c:21: > > /home/cvs/parisc/git-kernel/linus-linux-2.6/include/linux/pgtable.h: In function ‘clear_young_dirty_ptes’: > > /home/cvs/parisc/git-kernel/linus-linux-2.6/include/linux/pgtable.h:683:25: error: implicit declaration of function ‘ptep_test_and_clear_young’; > > did you mean ‘pmdp_test_and_clear_young’? [-Wimplicit-function-declaration] > >   683 |                         ptep_test_and_clear_young(vma, addr, ptep); > >       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~ > >       |                         pmdp_test_and_clear_young > > > > So, I think the answer is, that the local copy of ptep_get() is used in the parisc implementation of > > ptep_test_and_clear_young() function. > > > > Switching to the default include/linux/pgtable.h seems not easy doable.... > > Did you remove define for __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG in parisc version of pgtable.h? Indeed, I missed to remove that. Usama, if you want you can add the patch below to your patch set, thus simplifying your series? Helge ------ From: Helge Deller Date: Sat, 25 Jul 2026 19:19:55 +0200 Subject: [PATCH] parisc: Drop own implementations for ptep_get() and ptep_test_and_clear_young() Switch to the generic implementations, which are identical. Suggested-by: Usama Arif Suggested-by: John David Anglin Signed-off-by: Helge Deller diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h index 467b8547ac8b..d92dee9fef3f 100644 --- a/arch/parisc/include/asm/pgtable.h +++ b/arch/parisc/include/asm/pgtable.h @@ -432,25 +432,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) return pte; } -static inline pte_t ptep_get(pte_t *ptep) -{ - return READ_ONCE(*ptep); -} -#define ptep_get ptep_get - -static inline bool ptep_test_and_clear_young(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) -{ - pte_t pte; - - pte = ptep_get(ptep); - if (!pte_young(pte)) { - return false; - } - set_pte_at(vma->vm_mm, addr, ptep, pte_mkold(pte)); - return true; -} - bool ptep_clear_flush_young(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep); pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep); @@ -491,7 +472,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, #define HAVE_ARCH_UNMAPPED_AREA #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN -#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH #define __HAVE_ARCH_PTEP_CLEAR_FLUSH #define __HAVE_ARCH_PTEP_SET_WRPROTECT