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[209.85.221.176]) by smtp.gmail.com with ESMTPSA id r67-20020a1f2b46000000b00443c9140414sm1918150vkr.41.2023.05.10.00.14.22 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 May 2023 00:14:22 -0700 (PDT) Received: by mail-vk1-f176.google.com with SMTP id 71dfb90a1353d-44ffef66dabso3763566e0c.2 for ; Wed, 10 May 2023 00:14:22 -0700 (PDT) X-Received: by 2002:a05:6902:1147:b0:b99:4ac6:3c75 with SMTP id p7-20020a056902114700b00b994ac63c75mr18672301ybu.10.1683702842290; Wed, 10 May 2023 00:14:02 -0700 (PDT) MIME-Version: 1.0 References: <77a5d8c-406b-7068-4f17-23b7ac53bc83@google.com> <237c8410-ce61-94c-4260-7318ad6a4f3@google.com> In-Reply-To: <237c8410-ce61-94c-4260-7318ad6a4f3@google.com> From: Geert Uytterhoeven Date: Wed, 10 May 2023 09:13:50 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 05/23] m68k: allow pte_offset_map[_lock]() to fail To: Hugh Dickins Cc: Andrew Morton , Mike Kravetz , Mike Rapoport , "Kirill A. Shutemov" , Matthew Wilcox , David Hildenbrand , Suren Baghdasaryan , Qi Zheng , Russell King , Catalin Marinas , Will Deacon , Greg Ungerer , Michal Simek , Thomas Bogendoerfer , Helge Deller , John David Anglin , "Aneesh Kumar K.V" , Michael Ellerman , Alexandre Ghiti , Palmer Dabbelt , Heiko Carstens , Christian Borntraeger , Claudio Imbrenda , John Paul Adrian Glaubitz , "David S. Miller" , Chris Zankel , Max Filippov , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.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-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 95692140003 X-Rspam-User: X-Rspamd-Server: rspam06 X-Stat-Signature: ur6dw9zwtfqo7zsbo16s1sxwrzosacef X-HE-Tag: 1683702864-545531 X-HE-Meta: U2FsdGVkX18g00iJ6F8GVkERiBRua2YPt8GEScyqAZcqUUt1pIPqzbvjuaSO2M4wMBeG20/daMWNOboyhK92i4uHI4AnWd0IIDadSnRn8Eji5bzDy2w7ZXZxnnCT1KCwsNNjX6K40VBbkYCmng337xYqndzqJtJs/KjPShGJYNtQiuh4NIqBljYjE183rKgepMGxklkZsNTJe9nrJIVZBvC7iRHhTF6yLzEGV+xbyFMnpjQlNpOfiGYsQdD53RPlm7ZO9L08TEWFwB7/bT1k2AG2JpWdWd4t4sYd/rhT09oj2QIdCSPlh1LH01ikcxOaK3wCwVcochTHQrh6N4v0lM1NQhHzw4VZMynNQtBMqPRpNezscCHqEbuK9fwLckPaLNuySCKygsm/uiP5j+Aqd58ERqOZCFKXShUgwjFufTXtYWJrrVM1GiSJ1FBQosNi5ieBJ+hLtw6GKh2p4S5wjoC3+B2dwsepC0a2qy6Ajv4vAtniofu1gwTSs1Zr0x1pSGDbc5GCGWc7tftaXWBLJxGLNGzU7Mad5SePzt3F5bdEmwi/9HfeysJHnBQPQZd5v7XMlFLcA941sanzqBTW2fm5diS6/IH4kckP0bRYgnU5rcrW9si5gHZoQoaxoKxyzuFIy8nbn6zDa4ZvgTdjGzReQNlsUo7Zfw24NY40JldZJWjclk3o76ZYcoBAwQtqO87MN4UOJ1OC3SREBxCU02MqYdYnBn5O68zJp7UNEA+X7Re04BHRVGi/+EofKg6L2w7zkPdid08KCI5zEn5RZKuGclWUXR7dUoa+3e6lJlzmmxM2TeKllruLqT9ejkKacM9dTyZtok1j5NgvkzFJUHU3yo7hZagYULoGbmbO8+K87sz6mV7t+gA75LpYXhcrmu4ol5oYWzptKv8b6OpTFggs4w8NEbVEuGfLHdxLRoolb5TDBp0CuqdEUMU/wIv+YpIjKcWQNG9fG3ht5nr cK/GyA8Y 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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: Hi Hugh, Thanks for your patch! On Wed, May 10, 2023 at 6:48=E2=80=AFAM Hugh Dickins wro= te: > In rare transient cases, not yet made possible, pte_offset_map() and > pte_offset_map_lock() may not find a page table: handle appropriately. > > Restructure cf_tlb_miss() with a pte_unmap() (previously omitted) > at label out, followed by one local_irq_restore() for all. That's a bug fix, which should be a separate patch? > > Signed-off-by: Hugh Dickins > --- a/arch/m68k/include/asm/mmu_context.h > +++ b/arch/m68k/include/asm/mmu_context.h > @@ -99,7 +99,7 @@ static inline void load_ksp_mmu(struct task_struct *tas= k) > p4d_t *p4d; > pud_t *pud; > pmd_t *pmd; > - pte_t *pte; > + pte_t *pte =3D NULL; > unsigned long mmuar; > > local_irq_save(flags); > @@ -139,7 +139,7 @@ static inline void load_ksp_mmu(struct task_struct *t= ask) > > pte =3D (mmuar >=3D PAGE_OFFSET) ? pte_offset_kernel(pmd, mmuar) > : pte_offset_map(pmd, mmuar); > - if (pte_none(*pte) || !pte_present(*pte)) > + if (!pte || pte_none(*pte) || !pte_present(*pte)) > goto bug; If the absence of a pte is to become a non-abnormal case, it should probably jump to "end" instead, to avoid spamming the kernel log. > > set_pte(pte, pte_mkyoung(*pte)); > @@ -161,6 +161,8 @@ static inline void load_ksp_mmu(struct task_struct *t= ask) > bug: > pr_info("ksp load failed: mm=3D0x%p ksp=3D0x08%lx\n", mm, mmuar); > end: > + if (pte && mmuar < PAGE_OFFSET) > + pte_unmap(pte); Is this also a bugfix, not mentioned in the patch description? > local_irq_restore(flags); > } > Gr{oetje,eeting}s, Geert --=20 Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k= .org In personal conversations with technical people, I call myself a hacker. Bu= t when I'm talking to journalists I just say "programmer" or something like t= hat. -- Linus Torvalds