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[2003:cb:c71c:9800:fa4a:c1fc:a860:85af]) by smtp.gmail.com with ESMTPSA id q18-20020adfdfd2000000b002bdc129c8f6sm10260315wrn.43.2023.01.14.08.09.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 14 Jan 2023 08:09:37 -0800 (PST) Message-ID: <6aaad548-cf48-77fa-9d6c-db83d724b2eb@redhat.com> Date: Sat, 14 Jan 2023 17:09:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Hugh Dickins , John Hubbard , Jason Gunthorpe , Mike Rapoport , Yang Shi , Vlastimil Babka , Nadav Amit , Andrea Arcangeli , Peter Xu , linux-mm@kvack.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org References: <20230113171026.582290-1-david@redhat.com> <20230113171026.582290-2-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH mm-unstable v1 01/26] mm/debug_vm_pgtable: more pte_swp_exclusive() sanity checks In-Reply-To: <20230113171026.582290-2-david@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 3D3E11C001B X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: jrebh1ih6dz4k5et4xubeowyt6dzu7j8 X-HE-Tag: 1673712591-143478 X-HE-Meta: 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 8kIrr0eI O4XghouOEM+z3RjapBzm6B6IUDW9PKgAojqtbqiSyB2z133yyKwZBjneRLLkVDp9OxQJDo8/20IOZTGjkNDx7xeGawHEZmH8s2P7HXnm9UHdk/U1+zh1RwJgHY/zVcG/4fRXQUUwxDqZMzsufG8Mnr7u12CgYYJlxkp8t39eh5heH4RR5ZRuy1RwptL41OYGQPF7rJ092nBNr7jMKZOP6x0XT9IUck6h+B4jx/YbFYX5DL50= 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: On 13.01.23 18:10, David Hildenbrand wrote: > We want to implement __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures. > Let's extend our sanity checks, especially testing that our PTE bit > does not affect: > * is_swap_pte() -> pte_present() and pte_none() > * the swap entry + type > * pte_swp_soft_dirty() > > Especially, the pfn_pte() is dodgy when the swap PTE layout differs > heavily from ordinary PTEs. Let's properly construct a swap PTE from > swap type+offset. > > Signed-off-by: David Hildenbrand > --- The following fixup for !CONFIG_SWAP on top, which makes it compile for me and passes when booting on x86_64 with CONFIG_DEBUG_VM_PGTABLE: ... [ 0.347112] Loaded X.509 cert 'Build time autogenerated kernel key: ee6afc0578f6475656fec8a4f9d02832' [ 0.350112] debug_vm_pgtable: [debug_vm_pgtable ]: Validating architecture page table helpers [ 0.351217] page_owner is disabled ... From 6a6162e8af62a4b3f7b9d823fdfae86de3f34a9d Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Sat, 14 Jan 2023 16:47:12 +0100 Subject: [PATCH] fixup: mm/debug_vm_pgtable: more pte_swp_exclusive() sanity checks generic_max_swapfile_size() is only available with CONFIG_SWAP -- which makes sense, because without SWAP there are no swap files. Let's simply probe manually which bits we can obtain after storing them in a PTE, and properly call it "max swap offset", which is more generic for a swap entry. Reported-by: kernel test robot Signed-off-by: David Hildenbrand --- mm/debug_vm_pgtable.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 3da0cc380c35..af59cc7bd307 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -810,15 +810,17 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args) { static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args) { - unsigned long max_swapfile_size = generic_max_swapfile_size(); + unsigned long max_swap_offset; swp_entry_t entry, entry2; pte_t pte; pr_debug("Validating PTE swap exclusive\n"); + /* See generic_max_swapfile_size(): probe the maximum offset */ + max_swap_offset = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0, ~0UL)))); + /* Create a swp entry with all possible bits set */ - entry = swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, - max_swapfile_size - 1); + entry = swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, max_swap_offset); pte = swp_entry_to_pte(entry); WARN_ON(pte_swp_exclusive(pte)); -- 2.39.0 -- Thanks, David / dhildenb