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bh=Kacb8Xbrf8DRAJ5tFOl1Z0t/wE3X5H3fiIJQpBPvdwU=; b=BbD0kxstvem9mmwV6bRRvpd0ZuklBIVK62RDdU4bKrI4bjLMCekTiw2e86SB9lwqLyPpzh TdnhencRaswVeT90al2AA9bltvnY02orvsvJBM4q0PlUGtGCksMb8eFOoAj1VtENSfCaGn VxE8JYyz0y6lhVY/hAIgwbc5e6nYePnykhtCKqiWl3KX2jEqxD+Bc1+iiyVUda34eY8xPB Dubmz50xed8wXwaIzUPqoWwdnxDGdHb+xgmqf1wdRQbPp0OgA6ydrVAGcC7zSEudkqJdis E77mLczsBm2TPjTcL4x6RZcuc86oc1j3pSbN8JDRcr+hzZ8CH7xoi63nED2QcQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1694640504; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Kacb8Xbrf8DRAJ5tFOl1Z0t/wE3X5H3fiIJQpBPvdwU=; b=HQWDME7y3Hjcr/jWiVbXxp5p2zNDxv1YaX0Va71/8ymKrjUJQ+vdVZ9lCSVVFVlpOiIITN f2eLzZl7Uk7Ze1CQ== To: David Hildenbrand , Matthew Wilcox , Sean Christopherson , Andi Kleen , Josh Poimboeuf , Michal Hocko , Vlastimil Babka , Dave Hansen Cc: linux-mm@kvack.org, x86@kernel.org Subject: Re: [willy@infradead.org: Re: [syzbot] [mm?] BUG: Bad page map (7)] In-Reply-To: <2d760884-051a-372c-a33d-a4bfe2f25675@redhat.com> References: <2d760884-051a-372c-a33d-a4bfe2f25675@redhat.com> Date: Wed, 13 Sep 2023 23:28:23 +0200 Message-ID: <87jzstzrt4.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 86CC610000C X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 9boeuw7qttc9pqwagonanridw9xiw693 X-HE-Tag: 1694640506-453964 X-HE-Meta: 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 fKQXZPH+ GmtF7U3K/4jrQOFJupr6xjnvabJEPtEkd3Fzp15etn/8ZgcM0cKVrjsxFaMpHfaIj7rBH6vToPse6a6smdBi3FrfS1Nq+TrFra4Pbj/H3eJoH/hB9EO7RgxGLHHAaTDqLnIScfizxRIiohQ6i1PYgg248n8FkNnDmfPElHMG5Ymbwvow= 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 Mon, Sep 11 2023 at 19:50, David Hildenbrand wrote: >> #ifndef set_ptes >> /** >> * set_ptes - Map consecutive pages to a contiguous range of addresses. >> @@ -231,7 +235,10 @@ static inline void set_ptes(struct mm_struct *mm, unsigned long addr, >> if (--nr == 0) >> break; >> ptep++; >> - pte = __pte(pte_val(pte) + (1UL << PFN_PTE_SHIFT)); >> + if (__pte_needs_invert(pte_val(pte))) >> + pte = __pte(pte_val(pte) - (1UL << PFN_PTE_SHIFT)); >> + else >> + pte = __pte(pte_val(pte) + (1UL << PFN_PTE_SHIFT)); >> } > > Maybe we want some pte_advance() [or similar, you get the spirit] instead? > > Leaking this inverted-pte logic into common code really does look nasty. Yes please