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[85.229.14.155]) by smtp.gmail.com with ESMTPSA id w11-20020a19c50b000000b004f251cf3d31sm2908003lfe.153.2023.05.16.02.49.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 May 2023 02:49:21 -0700 (PDT) Date: Tue, 16 May 2023 11:49:19 +0200 From: Anders Roxell To: Lorenzo Stoakes 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 , Jens Axboe , Pavel Begunkov , Jason Gunthorpe , John Hubbard Subject: Re: [PATCH v5 3/6] mm/gup: remove vmas parameter from get_user_pages_remote() Message-ID: <20230516094919.GA411@mutt> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: BE03040010 X-Rspam-User: X-Rspamd-Server: rspam06 X-Stat-Signature: 15c3xfwbandmyhp6pten8dtt3wcktnen X-HE-Tag: 1684230564-306794 X-HE-Meta: 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 Ea0X8T1c 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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: On 2023-05-14 22:26, 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. > > We are able to perform these VMA operations as we already hold the > mmap_lock in order to be able to call get_user_pages_remote(). > > As part of this work we add get_user_page_vma_remote() which abstracts the > VMA lookup, error handling and decrementing the page reference count should > the VMA lookup fail. > > This forms part of a broader set of patches intended to eliminate the vmas > parameter altogether. > > Reviewed-by: Catalin Marinas (for arm64) > Acked-by: David Hildenbrand > Reviewed-by: Janosch Frank (for s390) > Signed-off-by: Lorenzo Stoakes > --- > arch/arm64/kernel/mte.c | 17 +++++++++-------- > arch/s390/kvm/interrupt.c | 2 +- > fs/exec.c | 2 +- > include/linux/mm.h | 34 +++++++++++++++++++++++++++++++--- > kernel/events/uprobes.c | 13 +++++-------- > mm/gup.c | 12 ++++-------- > mm/memory.c | 14 +++++++------- > mm/rmap.c | 2 +- > security/tomoyo/domain.c | 2 +- > virt/kvm/async_pf.c | 3 +-- > 10 files changed, 61 insertions(+), 40 deletions(-) > [...] > diff --git a/mm/memory.c b/mm/memory.c > index 146bb94764f8..63632a5eafc1 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -5590,7 +5590,6 @@ EXPORT_SYMBOL_GPL(generic_access_phys); > int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, > int len, unsigned int gup_flags) > { > - struct vm_area_struct *vma; > void *old_buf = buf; > int write = gup_flags & FOLL_WRITE; > > @@ -5599,13 +5598,15 @@ int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, > > /* ignore errors, just check how much was successfully transferred */ > while (len) { > - int bytes, ret, offset; > + int bytes, offset; > void *maddr; > - struct page *page = NULL; > + struct vm_area_struct *vma; > + struct page *page = get_user_page_vma_remote(mm, addr, > + gup_flags, &vma); > + > + if (IS_ERR_OR_NULL(page)) { > + int ret = 0; I see the warning below when building without CONFIG_HAVE_IOREMAP_PROT set. make --silent --keep-going --jobs=32 \ O=/home/anders/.cache/tuxmake/builds/1244/build ARCH=arm \ CROSS_COMPILE=arm-linux-gnueabihf- /home/anders/src/kernel/next/mm/memory.c: In function '__access_remote_vm': /home/anders/src/kernel/next/mm/memory.c:5608:29: warning: unused variable 'ret' [-Wunused-variable] 5608 | int ret = 0; | ^~~ > > - ret = get_user_pages_remote(mm, addr, 1, > - gup_flags, &page, &vma, NULL); > - if (ret <= 0) { > #ifndef CONFIG_HAVE_IOREMAP_PROT > break; > #else > @@ -5613,7 +5614,6 @@ int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, > * Check if this is a VM_IO | VM_PFNMAP VMA, which > * we can access using slightly different code. > */ > - vma = vma_lookup(mm, addr); > if (!vma) > break; > if (vma->vm_ops && vma->vm_ops->access) Cheers, Anders