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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 99AC6C47422 for ; Mon, 29 Jan 2024 06:27:48 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=FKTiWUxr; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TNddZ6bbnz3cTr for ; Mon, 29 Jan 2024 17:27:46 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=FKTiWUxr; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=145.40.73.55; helo=sin.source.kernel.org; envelope-from=aneesh.kumar@kernel.org; receiver=lists.ozlabs.org) Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4TNdcj2PnPz2ykn for ; Mon, 29 Jan 2024 17:27:01 +1100 (AEDT) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id DF545CE0FA7; Mon, 29 Jan 2024 06:26:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6125DC433C7; Mon, 29 Jan 2024 06:26:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706509615; bh=ozH9tUKz+Ib/lG38+cYJ5t0IlrhQYRHwhVjs+83kvFk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FKTiWUxrb7cFzx2xDm6e3IzeVPaq5sNNy6AMJU7zMTl8d9pQodtlZGlm0+YzLT30x w2C28C85p/J0bMimYFQG8ggI6bJDczw3OUCepptA1R7inKsJE5/S4r7FebEyfoTys4 cVEnjCc20pcWmhq3Ev0x1OG4mSnyZNip0Hv77m2xxdRbMyiN3kslrFGe4cOA6LXhAM jCybeoSeJpUVB5DQGWuxkNMDfx9C5eRQrGo9IA8AcVQPyz2Rk4PyuHUtnUoUbTC2NK yFRW0AO/ZfTYtTc2zXMeg9MCCcV81dqaFOQR0ZOr5g5bq4BENSR2ZQNIZShjH4YSB5 gExtduADKB/4A== Message-ID: <504f70be-deca-4f7f-b28c-d1ec2cf5a348@kernel.org> Date: Mon, 29 Jan 2024 11:56:49 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/debug_vm_pgtable: Fix BUG_ON with pud advanced test To: Anshuman Khandual , linux-mm@kvack.org, akpm@linux-foundation.org References: <20240129060022.68044-1-aneesh.kumar@kernel.org> <1b3c1513-826d-4908-93c3-212a6f1b2d74@arm.com> Content-Language: en-US From: "Aneesh Kumar K.V" In-Reply-To: <1b3c1513-826d-4908-93c3-212a6f1b2d74@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 1/29/24 11:52 AM, Anshuman Khandual wrote: > > > On 1/29/24 11:30, Aneesh Kumar K.V (IBM) wrote: >> Architectures like powerpc add debug checks to ensure we find only devmap >> PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM. >> This patch marks the ptes used for PUD advanced test devmap pte entries >> so that we don't hit on debug checks on architecture like ppc64 as >> below. >> >> WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 radix__pud_hugepage_update+0x38/0x138 >> .... >> NIP [c0000000000a7004] radix__pud_hugepage_update+0x38/0x138 >> LR [c0000000000a77a8] radix__pudp_huge_get_and_clear+0x28/0x60 >> Call Trace: >> [c000000004a2f950] [c000000004a2f9a0] 0xc000000004a2f9a0 (unreliable) >> [c000000004a2f980] [000d34c100000000] 0xd34c100000000 >> [c000000004a2f9a0] [c00000000206ba98] pud_advanced_tests+0x118/0x334 >> [c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48 >> [c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388 >> >> Also >> >> kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202! >> .... >> >> NIP [c000000000096510] pudp_huge_get_and_clear_full+0x98/0x174 >> LR [c00000000206bb34] pud_advanced_tests+0x1b4/0x334 >> Call Trace: >> [c000000004a2f950] [000d34c100000000] 0xd34c100000000 (unreliable) >> [c000000004a2f9a0] [c00000000206bb34] pud_advanced_tests+0x1b4/0x334 >> [c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48 >> [c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388 >> >> Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage") >> Signed-off-by: Aneesh Kumar K.V (IBM) >> --- >> mm/debug_vm_pgtable.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >> index 5662e29fe253..65c19025da3d 100644 >> --- a/mm/debug_vm_pgtable.c >> +++ b/mm/debug_vm_pgtable.c >> @@ -362,6 +362,12 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args) >> vaddr &= HPAGE_PUD_MASK; >> >> pud = pfn_pud(args->pud_pfn, args->page_prot); >> + /* >> + * Some architectures have debug checks to make sure >> + * huge pud mapping are only found with devmap entries >> + * For now test with only devmap entries. >> + */ > Do you see this behaviour to be changed in powerpc anytime soon ? Otherwise > these pud_mkdevmap() based work arounds, might be required to stick around > for longer just to prevent powerpc specific triggers. Given PUD transparent > huge pages i.e HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD are just supported on x86 > and powerpc platforms, could not this problem be solved in a more uniform > manner. > IIUC pud level transparent hugepages are only supported with devmap entries even on x86. We don't do anonymous pud hugepage. >> + pud = pud_mkdevmap(pud); >> set_pud_at(args->mm, vaddr, args->pudp, pud); >> flush_dcache_page(page); >> pudp_set_wrprotect(args->mm, vaddr, args->pudp); >> @@ -374,6 +380,7 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args) >> WARN_ON(!pud_none(pud)); >> #endif /* __PAGETABLE_PMD_FOLDED */ >> pud = pfn_pud(args->pud_pfn, args->page_prot); >> + pud = pud_mkdevmap(pud); >> pud = pud_wrprotect(pud); >> pud = pud_mkclean(pud); >> set_pud_at(args->mm, vaddr, args->pudp, pud); >> @@ -391,6 +398,7 @@ static void __init pud_advanced_tests(struct pgtable_debug_args *args) >> #endif /* __PAGETABLE_PMD_FOLDED */ >> >> pud = pfn_pud(args->pud_pfn, args->page_prot); >> + pud = pud_mkdevmap(pud); >> pud = pud_mkyoung(pud); >> set_pud_at(args->mm, vaddr, args->pudp, pud); >> flush_dcache_page(page); -aneesh