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Tue, 24 Jun 2025 08:03:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id PDTcDd5bWmjcAQAAD6G6ig (envelope-from ); Tue, 24 Jun 2025 08:03:42 +0000 Message-ID: <62c4045c-3881-4df2-8f36-109346c18e13@suse.cz> Date: Tue, 24 Jun 2025 10:03:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 1/2] mm, madvise: simplify anon_name handling To: Lorenzo Stoakes Cc: Andrew Morton , "Liam R. Howlett" , David Hildenbrand , Jann Horn , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Colin Cross , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250623-anon_name_cleanup-v1-0-04c94384046f@suse.cz> <20250623-anon_name_cleanup-v1-1-04c94384046f@suse.cz> <7fd9d523-d331-498d-8b67-2b525c0de37d@lucifer.local> Content-Language: en-US From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <7fd9d523-d331-498d-8b67-2b525c0de37d@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 0741D1C0009 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: aatkndjc5oxciehknybjui6313g9jx86 X-HE-Tag: 1750752223-939871 X-HE-Meta: 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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: List-Subscribe: List-Unsubscribe: On 6/23/25 18:56, Lorenzo Stoakes wrote: > On Mon, Jun 23, 2025 at 04:59:50PM +0200, Vlastimil Babka wrote: > I think we can actually avoid this altogether... So we could separate this into two functions: > > tatic int madvise_update_vma_anon_name(struct madvise_behavior *madv_behavior) > { > struct vm_area_struct *vma = madv_behavior->vma; > VMA_ITERATOR(vmi, madv_behavior->mm, range->start); > struct madvise_behavior_range *range = &madv_behavior->range; > struct anon_vma_name *anon_name = madv_behavior->anon_name; > > if (anon_vma_name_eq(anon_vma_name(vma), anon_name)) > rturn 0; > > vma = vma_modify_flags_name(&vmi, madv_behavior->prev, vma, > range->start, range->end, vma->vm_flags, anon_name); > if (IS_ERR(vma)) > return PTR_ERR(vma); > > madv_behavior->vma = vma; > > /* vm_flags is protected by the mmap_lock held in write mode. */ > vma_start_write(vma); > return replace_anon_vma_name(vma, anon_name); > } > > /* > * Update the vm_flags and/or anon_name on region of a vma, splitting it or > * merging it as necessary. Must be called with mmap_lock held for writing. > */ > static int madvise_update_vma(vm_flags_t new_flags, > struct madvise_behavior *madv_behavior) > { > struct vm_area_struct *vma = madv_behavior->vma; > struct madvise_behavior_range *range = &madv_behavior->range; > VMA_ITERATOR(vmi, madv_behavior->mm, range->start); > > if (new_flags == vma->vm_flags) > return 0; > > vma = vma_modify_flags(&vmi, madv_behavior->prev, vma, > range->start, range->end, new_flags); Using vma_modify_flags() is a great suggestion to avoid passing the existing vma->anon_name explicitly, thanks! I believe I can do that without duplicating the whole madvise_update_vma() function and it doesn't look that bad so I'll try going that way in v2. This also addresses Suren's concerns as there will be no local variable pointing to the vma->anon_name that can become a UAF again by future changes so we shouldn't need the warning comments either. Thanks!