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Mon, 24 Jul 2023 08:46:58 -0700 (PDT) MIME-Version: 1.0 References: <20230711202047.3818697-1-willy@infradead.org> <20230711202047.3818697-6-willy@infradead.org> In-Reply-To: <20230711202047.3818697-6-willy@infradead.org> From: Jann Horn Date: Mon, 24 Jul 2023 17:46:21 +0200 Message-ID: Subject: Re: [PATCH v2 5/9] mm: Move FAULT_FLAG_VMA_LOCK check down in handle_pte_fault() To: "Matthew Wilcox (Oracle)" Cc: linux-mm@kvack.org, Arjun Roy , Eric Dumazet , Suren Baghdasaryan , linux-fsdevel@vger.kernel.org, Punit Agrawal Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: F28404000D X-Rspam-User: X-Stat-Signature: 5z7fnju3yxf9jbfiwog3sbguwx43to6y X-Rspamd-Server: rspam01 X-HE-Tag: 1690213619-805580 X-HE-Meta: U2FsdGVkX191uhAlyi6Vhbwa9KX+QZefpy96zBSq7b5B1X5Z4I2eP5sy2jYsssjlo/XVFxi/ORzF/9IJzpxC9WrQEYuJQBQR7rPzjduXOTMgkuV1gM+wA6AcAmbQYM1E+2IKEEzpCcjLSFwORIQQWTn6qtCNZwOjApS9CWe1o+d2kHXPa652gn9pDALR78yofm15GfFS+nTDF/Q5/7Yccwrz8C+D9ctJbPc8G/wnButM+2+z2oHoy2Os4EH1VwNZr5sz7lAX/2L2oVVNU/OotrnLo2ErLLXJE/g6WirxkfKKU0HkAcrjDXuxYpsvbHxZ7154fF+Tlxf7eysgUbwfb0Thyikb7Oc2bgnR2wD/lKGbCwfPhFaOVf+2Q+nLOkjuO+5n6a1er2t3O4QsTaexV8/vRMEhayfdU+/LJ6RIul9ZQnIpLAGXCffvIN/UEjn4ImEbUJr/g+7nVInVQ3/ah+rN7Ql8RRpC5zRDNHtazQxmYgJoJMjI84swyqvkMuUirccp08YrG3GQ4sDwSwqscWD92UmZHgT2+k51dErC5H3zgL0Dp3FQV/AMEPNxZtF1FmExFQoaSQ5knrS1AygX6qti8RiDdsUf1Okpk4S27boYLXSOjBQe/oIIlFOwSl6i8ra6vbxEakTGMv2FTWZvJL4wM/qlZY7bMPowLX+CN/tmxFaEJRwLmF9kenw1fhmFO743VWdFeYlFqOVfzmJWodg963LYFwXXRYhRhUUyP0OJu2d5/Sp4K5E6L2m253g+0f9VWGcdUeIoUN6v46hRWWdxZvXe02/0aosZyN3SIe3FLOfQ2ocrwFqwSKx1dvg7Ch+pefMwydX3oDGusryo2d2PluKwcr0L7cQTo31awuf5UIvEUZjsrD2c9nXWds9NDGqDxRxLyrp+d3qRbMiZTnnJJItEjoSjClVtLNG7nzOQLa4Ous9/9d4c2KrapK14yZLBwfyTsWMMquLeu5h qq+ImlD1 CygIBfht4zEe3FsHmix4/B0rI+8CfEUzSLszkTRkTb6dCd56m9MQyva/9dgU9F8bxB18LBFS6UUoQmreCUtUiJAzEYiFXygP6FuXm06jinhVXNn7ncVp9ww5ZGZV4onI6spqE+CG5wbb+q5UKjK+ahsBCbykiFWRkKBN+koeWhkqRHQPmNAFvOXKi/wWetS6/Uj6/uMBmJml3lHLRDpwGOrrT330iULRNtD5wmmYLSUDoOuuW/q+E7bn0UEWMT5WX0u2dIIIWBrizJUcfzR3hGtS7CCXQU7A1hcQrtjSsmOnnXR9y1mlrIrvq6GFgAXrU3ZBurmXh66ScAmw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.003726, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jul 11, 2023 at 10:20=E2=80=AFPM Matthew Wilcox (Oracle) wrote: > Call do_pte_missing() under the VMA lock ... then immediately retry > in do_fault(). > > Signed-off-by: Matthew Wilcox (Oracle) > --- [...] > @@ -4961,6 +4961,11 @@ static vm_fault_t handle_pte_fault(struct vm_fault= *vmf) > if (!vmf->pte) > return do_pte_missing(vmf); > > + if ((vmf->flags & FAULT_FLAG_VMA_LOCK) && !vma_is_anonymous(vmf->= vma)) { > + vma_end_read(vmf->vma); > + return VM_FAULT_RETRY; > + } At this point we can have vmf->pte mapped, right? Does this mean this bailout leaks a kmap_local() on CONFIG_HIGHPTE? > if (!pte_present(vmf->orig_pte)) > return do_swap_page(vmf);