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[86.156.84.164]) by smtp.gmail.com with ESMTPSA id hn3-20020a05600ca38300b003f16ebdc93esm6117802wmb.24.2023.04.17.06.13.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Apr 2023 06:13:40 -0700 (PDT) Date: Mon, 17 Apr 2023 14:13:39 +0100 From: Lorenzo Stoakes To: Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Matthew Wilcox , David Hildenbrand , linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, Catalin Marinas , Will Deacon , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Eric Biederman , Kees Cook , Alexander Viro , Christian Brauner , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Kentaro Takeda , Tetsuo Handa , Paul Moore , James Morris , "Serge E . Hallyn" , Paolo Bonzini Subject: Re: [PATCH 3/7] mm/gup: remove vmas parameter from get_user_pages_remote() Message-ID: <9be77e7e-4531-4e1c-9e0d-4edbb5ad3bd5@lucifer.local> References: <5a4cf1ebf1c6cdfabbf2f5209facb0180dd20006.1681508038.git.lstoakes@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 88AC14001F X-Stat-Signature: cof86fadnu4434pdzei45xy5g4tr1jzd X-Rspam-User: X-HE-Tag: 1681737222-858263 X-HE-Meta: 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 Qldf2Vel FtRx7tgyDQV1mRlMITikEXBPVchK7zVVwDeBhUD7P+6+tTDFJrEY4mpM+hJMPhOzOtHBNDD7rLcgrT1rrfLVCZVrg77ClmVG735FCrrTIwXPVodhrbb/qFhlPvq4pLlMOEsw42AhCHHRMSB8J0rRyqarRiGZrXEX74gA7wYMpIS/TS5CYDQm7iI0FXqXA4cAFfYBM//Dcd0+rZ74v0rBCqwjFBJbsz9EmnPSQ+Qm9NnCP0OtqGFxMLuXFlSvtRKEp/n5Js/i823HRwaekrrYWys9GwD+xweeWz7IgXj2dZyQTZowO+6voBXaeCFHZIBTLZapkdmLCERCRN+5HIFClCTeP8fCfO4mqf88zIDRkyAamm8YqX6CsTg/kGWfAKjj99NE2DybnCEVvBWHF0oIiMNcwHufYAKft3gL41M/vCuusdzxp5mWoV/RzBBhM6mZQzZo/Wj65ycz/6mMv5/c3ByEsRoFW0c66rzSKIKFQEE4WONY= 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, Apr 17, 2023 at 10:09:36AM -0300, Jason Gunthorpe wrote: > On Sat, Apr 15, 2023 at 12:27:31AM +0100, Lorenzo Stoakes wrote: > > The only instances of get_user_pages_remote() invocations which used the > > vmas parameter were for a single page which can instead simply look up the > > VMA directly. In particular:- > > > > - __update_ref_ctr() looked up the VMA but did nothing with it so we simply > > remove it. > > > > - __access_remote_vm() was already using vma_lookup() when the original > > lookup failed so by doing the lookup directly this also de-duplicates the > > code. > > > > This forms part of a broader set of patches intended to eliminate the vmas > > parameter altogether. > > > > Signed-off-by: Lorenzo Stoakes > > --- > > arch/arm64/kernel/mte.c | 5 +++-- > > arch/s390/kvm/interrupt.c | 2 +- > > fs/exec.c | 2 +- > > include/linux/mm.h | 2 +- > > kernel/events/uprobes.c | 10 +++++----- > > mm/gup.c | 12 ++++-------- > > mm/memory.c | 9 +++++---- > > mm/rmap.c | 2 +- > > security/tomoyo/domain.c | 2 +- > > virt/kvm/async_pf.c | 3 +-- > > 10 files changed, 23 insertions(+), 26 deletions(-) > > > > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > > index f5bcb0dc6267..74d8d4007dec 100644 > > --- a/arch/arm64/kernel/mte.c > > +++ b/arch/arm64/kernel/mte.c > > @@ -437,8 +437,9 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr, > > struct page *page = NULL; > > > > ret = get_user_pages_remote(mm, addr, 1, gup_flags, &page, > > - &vma, NULL); > > - if (ret <= 0) > > + NULL); > > + vma = vma_lookup(mm, addr); > > + if (ret <= 0 || !vma) > > break; > > Given the slightly tricky error handling, it would make sense to turn > this pattern into a helper function: > > page = get_single_user_page_locked(mm, addr, gup_flags, &vma); > if (IS_ERR(page)) > [..] > > static inline struct page *get_single_user_page_locked(struct mm_struct *mm, > unsigned long addr, int gup_flags, struct vm_area_struct **vma) > { > struct page *page; > int ret; > > ret = get_user_pages_remote(*mm, addr, 1, gup_flags, &page, NULL, NULL); > if (ret < 0) > return ERR_PTR(ret); > if (WARN_ON(ret == 0)) > return ERR_PTR(-EINVAL); > *vma = vma_lookup(mm, addr); > if (WARN_ON(!*vma) { > put_user_page(page); > return ERR_PTR(-EINVAL); > } > return page; > } > > It could be its own patch so this change was just a mechanical removal > of NULL > > Jason > Agreed, I think this would work better as a follow up patch however so as not to distract too much from the core change. I feel like there are quite a few things we can follow up on including assessing whether we might be able to use _fast() paths in places (I haven't assessed this yet).