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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1B587CCFA18 for ; Sat, 8 Nov 2025 20:18:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 689938E000A; Sat, 8 Nov 2025 15:18:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 639408E0003; Sat, 8 Nov 2025 15:18:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5011F8E000A; Sat, 8 Nov 2025 15:18:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 38EEC8E0003 for ; Sat, 8 Nov 2025 15:18:45 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id CB4E04C0E6 for ; Sat, 8 Nov 2025 20:18:44 +0000 (UTC) X-FDA: 84088552968.06.7A69D3F Received: from mail-pl1-f182.google.com (mail-pl1-f182.google.com [209.85.214.182]) by imf27.hostedemail.com (Postfix) with ESMTP id 2772940002 for ; Sat, 8 Nov 2025 20:18:42 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=C+pyQQfK; spf=pass (imf27.hostedemail.com: domain of ritesh.list@gmail.com designates 209.85.214.182 as permitted sender) smtp.mailfrom=ritesh.list@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1762633123; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references:dkim-signature; bh=eptMmi/rSmOF7zh3lnbB0jvPX8L9rhMmLXfTARMvAA4=; b=38drfC0PJLlYvkE6VWnSa4P5Inanskf55lkfmiadJWbdXQPBHeRnnApaPNoSPA/gQuY0je 0Ib+/qLcIJ6EUGn8AjdnzHlZjjPrLWwfYDGh0L6xnwuN+1wVDbCOX87summvaNHYBSvPyo D64RV0vjjs2dp2IitoFtDKqpxC8rphI= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=C+pyQQfK; spf=pass (imf27.hostedemail.com: domain of ritesh.list@gmail.com designates 209.85.214.182 as permitted sender) smtp.mailfrom=ritesh.list@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1762633123; a=rsa-sha256; cv=none; b=UH9eZaR6VPuHGdclQLB2KlCjGGi9exMaWRfL42shUPgvBq6pFyx53wF2N1EbFo6JquB76t 38D4KoF7D62B82gdJ0gq1vQa+f93sdsYVI3VVfnJd0SuDKS1jZ/ilYuMKNkE+kcB4x07KM LX+aPEmcdU/wROFbALha8snMlu6aqnI= Received: by mail-pl1-f182.google.com with SMTP id d9443c01a7336-2958db8ae4fso14852075ad.2 for ; Sat, 08 Nov 2025 12:18:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1762633121; x=1763237921; darn=kvack.org; h=references:message-id:date:in-reply-to:subject:cc:to:from:from:to :cc:subject:date:message-id:reply-to; bh=eptMmi/rSmOF7zh3lnbB0jvPX8L9rhMmLXfTARMvAA4=; b=C+pyQQfKssAYE8SxFc6gr4pDMavEhN7575X5/IEjjHJ3IPt5kmokrAth8bDAHbadn7 lHQMmNNEWDkOuYmZC/L3f2wLy65BiXn1vIwPkg60bT+tDVeU0biNx/8uJUX7doQ8rKjP xdZSi/jCdsLsWZKUMlTcWj78xquygIU05+AEkNW9cIlPwuGtUnsXdur/at67BgDMu1e1 G1bS575euq6Wn4u6eZLjwyOlH66ED5GuMT6opxlizPbGE7um+xgDchVWMlfHiYGJtnyI merLjL9zevgIVsaBQleNbnGiwKx/ykWxErbCdhuUTXNhgeMue3OdxJaqDXmDriVXbVx7 MsCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762633121; x=1763237921; h=references:message-id:date:in-reply-to:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=eptMmi/rSmOF7zh3lnbB0jvPX8L9rhMmLXfTARMvAA4=; b=P2Lct8XI3Db3I/dHH3qS5YlwBy0xlYC+6dhL3L6SurrfgpDdK9Nkjyh6nvkgfzvQaP DvZVDwA/JJwAXYsuS81iWtXycW7VTLcuRzsQVVd+3YhsG/9IHbX4Q01C/0caMOI6QI4b sR5MDvLKewerLV7xD5DB0k3j+WMPXIKYpDsKon9ZncBb8wG435FynwcYDw7WDK2K8SWJ X+BdwRZY4AHK0DFvD+PyvTnPzyDKRRVmptYisyR6WMoauQVOwZspnxTkOAqFOfBv8egL 43aURha71g7kuhA/cDnH2o242iPUPc6KE0ec+AAtB/pQDoVSLQKLmW8ECndAf0oxkVXJ N7Ag== X-Forwarded-Encrypted: i=1; AJvYcCVn0AOICtAAMWR59pzisMMnMEuVMsjtJh+ThhXQw1sHQKo4A//NOEjrKSM+WDoOcmEaomGsCq2dxQ==@kvack.org X-Gm-Message-State: AOJu0YxFiC+6PDh8BR7KHr67UaZYZVyV5WwxO+QuOv6x6Skapo1bXiRG uoPPi8jkSE0jrVhSh2YNvrjNLihBG1MPAZ+Eti4SKuYjIIiV2SbORRpuHZRDiIGVUWU= X-Gm-Gg: ASbGnctilpaf+5sss6mP+8X0AxsplrWnyHRs+PiFw6Gew3U0dILAM5E4AgZFr0FADYn ruhqsu9cZHX8bqJm9MQYDq/GZIZBZPUO5NBnA5wNmxi82jex84igK6eCx1zhGmhZmbaGG6VKrmJ N2iwKlNFbtrI5OXGKnfnli39Ar/a59ljDKhrwSZwxHYLNLMWT0y100o6KW/OMLkzoy6KRpO5Tjt 8QxozZQ9Uwzp0w17TLwyxL+rWN+VxOFbsliGTKJLwSunkpBNkgvRk94X40mHp4z80E4dR3Y8p9J JsGEMwAt/+TgWF+F/PYPNLJ/0dBYWZmmYK37xyWJvYRyMC1+r3lmdiTMY1+KUdHMAUAPF/85QcP 7U2lqeTmC3xqqAjhacUE6nQoSww89gGzu54YvOc+8A53CETtUpEVY9L6hdS9YjEBJLojFaQ== X-Google-Smtp-Source: AGHT+IFb5ZIMhb48UQ+0j2VRNphIuxham09NgnX5MSt7QH3z4h9Q5UU4rBsGOgTmioZaQIMKF6pn6w== X-Received: by 2002:a17:903:f83:b0:295:5613:c19f with SMTP id d9443c01a7336-297e56f6b9amr42076845ad.42.1762633121076; Sat, 08 Nov 2025 12:18:41 -0800 (PST) Received: from dw-tp ([171.76.85.117]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-297d766efe6sm44719285ad.49.2025.11.08.12.18.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Nov 2025 12:18:40 -0800 (PST) From: Ritesh Harjani (IBM) To: Dave Vasilevsky via B4 Relay , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Nadav Amit , "Peter Zijlstra (Intel)" , Andrew Morton Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Dave Vasilevsky , linux-mm@kvack.org Subject: Re: [PATCH] powerpc: Fix mprotect on book3s32 In-Reply-To: <20251027-vasi-mprotect-g3-v1-1-3c5187085f9a@vasilevsky.ca> Date: Sun, 09 Nov 2025 00:46:04 +0530 Message-ID: <878qgg49or.ritesh.list@gmail.com> References: <20251027-vasi-mprotect-g3-v1-1-3c5187085f9a@vasilevsky.ca> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 2772940002 X-Stat-Signature: x3os8znzzw1u9sgzuzrthapu5foqdjb7 X-Rspam-User: X-HE-Tag: 1762633122-998947 X-HE-Meta: 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 yeeLSkpN 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: ++linux-mm to get some pointers on how to test such mmu_gather changes Dave Vasilevsky via B4 Relay writes: > From: Dave Vasilevsky > > On 32-bit book3s with hash-MMUs, tlb_flush() was a no-op. This was > unnoticed because all uses until recently were for unmaps, and thus > handled by __tlb_remove_tlb_entry(). > > After commit 4a18419f71cd ("mm/mprotect: use mmu_gather") in kernel 5.19, > tlb_gather_mmu() started being used for mprotect as well. This caused > mprotect to simply not work on these machines: > > int *ptr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, > MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); > *ptr = 1; // force HPTE to be created > mprotect(ptr, 4096, PROT_READ); > *ptr = 2; // should segfault, but succeeds I am surprised how come this was not caught? Don't we have any straight forward selftest for this? Not just mprotect then right.. Many other MM paths must also be using mmu_gather right? > > Fixed by making tlb_flush() actually flush TLB pages. This finally > agrees with the behaviour of boot3s64's tlb_flush(). > > Fixes: 4a18419f71cd ("mm/mprotect: use mmu_gather") > Signed-off-by: Dave Vasilevsky > --- > arch/powerpc/include/asm/book3s/32/tlbflush.h | 8 ++++++-- > arch/powerpc/mm/book3s32/tlb.c | 6 ++++++ > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/include/asm/book3s/32/tlbflush.h b/arch/powerpc/include/asm/book3s/32/tlbflush.h > index e43534da5207aa3b0cb3c07b78e29b833c141f3f..b8c587ad2ea954f179246a57d6e86e45e91dcfdc 100644 > --- a/arch/powerpc/include/asm/book3s/32/tlbflush.h > +++ b/arch/powerpc/include/asm/book3s/32/tlbflush.h > @@ -11,6 +11,7 @@ > void hash__flush_tlb_mm(struct mm_struct *mm); > void hash__flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr); > void hash__flush_range(struct mm_struct *mm, unsigned long start, unsigned long end); > +void hash__flush_gather(struct mmu_gather *tlb); > > #ifdef CONFIG_SMP > void _tlbie(unsigned long address); > @@ -28,9 +29,12 @@ void _tlbia(void); > */ > static inline void tlb_flush(struct mmu_gather *tlb) > { > - /* 603 needs to flush the whole TLB here since it doesn't use a hash table. */ > - if (!mmu_has_feature(MMU_FTR_HPTE_TABLE)) > + if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) { > + hash__flush_gather(tlb); > + } else { > + /* 603 needs to flush the whole TLB here since it doesn't use a hash table. */ > _tlbia(); > + } > } > > static inline void flush_range(struct mm_struct *mm, unsigned long start, unsigned long end) > diff --git a/arch/powerpc/mm/book3s32/tlb.c b/arch/powerpc/mm/book3s32/tlb.c > index 9ad6b56bfec96e989b96f027d075ad5812500854..3da95ecfbbb296303082e378425e92a5fbdbfac8 100644 > --- a/arch/powerpc/mm/book3s32/tlb.c > +++ b/arch/powerpc/mm/book3s32/tlb.c > @@ -105,3 +105,9 @@ void hash__flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr) > flush_hash_pages(mm->context.id, vmaddr, pmd_val(*pmd), 1); > } > EXPORT_SYMBOL(hash__flush_tlb_page); > + > +void hash__flush_gather(struct mmu_gather *tlb) > +{ > + hash__flush_range(tlb->mm, tlb->start, tlb->end); > +} > +EXPORT_SYMBOL(hash__flush_gather); Shouldn't we flush all if we get tlb_flush request for full mm? e.g. Something like this maybe? +void hash__tlb_flush(struct mmu_gather *tlb) +{ + if (tlb->fullmm || tlb->need_flush_all) + hash__flush_tlb_mm(tlb->mm); + else + hash__flush_range(tlb->mm, tlb->start, tlb->end); +} It will be quicker if someone already has a set of tests which we can run to validate. If not, I will take a look and see what tests one can run to validate mmu_gather feature. > > --- > base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa > change-id: 20251027-vasi-mprotect-g3-f8f5278d4140 > > Best regards, > -- > Dave Vasilevsky Thanks again for pointing this out. How did you find this though? What hardware do you use? -ritesh