Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756885AbcJSJFA (ORCPT ); Wed, 19 Oct 2016 05:05:00 -0400 Received: from mx2.suse.de ([195.135.220.15]:36507 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756080AbcJSJDy (ORCPT ); Wed, 19 Oct 2016 05:03:54 -0400 Date: Wed, 19 Oct 2016 09:47:07 +0200 From: Jan Kara To: Lorenzo Stoakes Cc: linux-mm@kvack.org, Linus Torvalds , Jan Kara , Hugh Dickins , Dave Hansen , Rik van Riel , Mel Gorman , Andrew Morton , adi-buildroot-devel@lists.sourceforge.net, ceph-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, kvm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cris-kernel@axis.com, linux-fbdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mips@linux-mips.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-scsi@vger.kernel.org, linux-security-module@vger.kernel.org, linux-sh@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 07/10] mm: replace get_user_pages_remote() write/force parameters with gup_flags Message-ID: <20161019074707.GO29967@quack2.suse.cz> References: <20161013002020.3062-1-lstoakes@gmail.com> <20161013002020.3062-8-lstoakes@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161013002020.3062-8-lstoakes@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10151 Lines: 272 On Thu 13-10-16 01:20:17, Lorenzo Stoakes wrote: > This patch removes the write and force parameters from get_user_pages_remote() > and replaces them with a gup_flags parameter to make the use of FOLL_FORCE > explicit in callers as use of this flag can result in surprising behaviour (and > hence bugs) within the mm subsystem. > > Signed-off-by: Lorenzo Stoakes Looks good. You can add: Reviewed-by: Jan Kara Honza > --- > drivers/gpu/drm/etnaviv/etnaviv_gem.c | 7 +++++-- > drivers/gpu/drm/i915/i915_gem_userptr.c | 6 +++++- > drivers/infiniband/core/umem_odp.c | 7 +++++-- > fs/exec.c | 9 +++++++-- > include/linux/mm.h | 2 +- > kernel/events/uprobes.c | 6 ++++-- > mm/gup.c | 22 +++++++--------------- > mm/memory.c | 6 +++++- > security/tomoyo/domain.c | 2 +- > 9 files changed, 40 insertions(+), 27 deletions(-) > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > index 5ce3603..0370b84 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > @@ -748,19 +748,22 @@ static struct page **etnaviv_gem_userptr_do_get_pages( > int ret = 0, pinned, npages = etnaviv_obj->base.size >> PAGE_SHIFT; > struct page **pvec; > uintptr_t ptr; > + unsigned int flags = 0; > > pvec = drm_malloc_ab(npages, sizeof(struct page *)); > if (!pvec) > return ERR_PTR(-ENOMEM); > > + if (!etnaviv_obj->userptr.ro) > + flags |= FOLL_WRITE; > + > pinned = 0; > ptr = etnaviv_obj->userptr.ptr; > > down_read(&mm->mmap_sem); > while (pinned < npages) { > ret = get_user_pages_remote(task, mm, ptr, npages - pinned, > - !etnaviv_obj->userptr.ro, 0, > - pvec + pinned, NULL); > + flags, pvec + pinned, NULL); > if (ret < 0) > break; > > diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c > index e537930..c6f780f 100644 > --- a/drivers/gpu/drm/i915/i915_gem_userptr.c > +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c > @@ -508,6 +508,10 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) > pvec = drm_malloc_gfp(npages, sizeof(struct page *), GFP_TEMPORARY); > if (pvec != NULL) { > struct mm_struct *mm = obj->userptr.mm->mm; > + unsigned int flags = 0; > + > + if (!obj->userptr.read_only) > + flags |= FOLL_WRITE; > > ret = -EFAULT; > if (atomic_inc_not_zero(&mm->mm_users)) { > @@ -517,7 +521,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) > (work->task, mm, > obj->userptr.ptr + pinned * PAGE_SIZE, > npages - pinned, > - !obj->userptr.read_only, 0, > + flags, > pvec + pinned, NULL); > if (ret < 0) > break; > diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c > index 75077a0..1f0fe32 100644 > --- a/drivers/infiniband/core/umem_odp.c > +++ b/drivers/infiniband/core/umem_odp.c > @@ -527,6 +527,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, > u64 off; > int j, k, ret = 0, start_idx, npages = 0; > u64 base_virt_addr; > + unsigned int flags = 0; > > if (access_mask == 0) > return -EINVAL; > @@ -556,6 +557,9 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, > goto out_put_task; > } > > + if (access_mask & ODP_WRITE_ALLOWED_BIT) > + flags |= FOLL_WRITE; > + > start_idx = (user_virt - ib_umem_start(umem)) >> PAGE_SHIFT; > k = start_idx; > > @@ -574,8 +578,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, > */ > npages = get_user_pages_remote(owning_process, owning_mm, > user_virt, gup_num_pages, > - access_mask & ODP_WRITE_ALLOWED_BIT, > - 0, local_page_list, NULL); > + flags, local_page_list, NULL); > up_read(&owning_mm->mmap_sem); > > if (npages < 0) > diff --git a/fs/exec.c b/fs/exec.c > index 6fcfb3f..4e497b9 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -191,6 +191,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, > { > struct page *page; > int ret; > + unsigned int gup_flags = FOLL_FORCE; > > #ifdef CONFIG_STACK_GROWSUP > if (write) { > @@ -199,12 +200,16 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, > return NULL; > } > #endif > + > + if (write) > + gup_flags |= FOLL_WRITE; > + > /* > * We are doing an exec(). 'current' is the process > * doing the exec and bprm->mm is the new process's mm. > */ > - ret = get_user_pages_remote(current, bprm->mm, pos, 1, write, > - 1, &page, NULL); > + ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags, > + &page, NULL); > if (ret <= 0) > return NULL; > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 686a477..2a481d3 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1276,7 +1276,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > struct vm_area_struct **vmas, int *nonblocking); > long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, > unsigned long start, unsigned long nr_pages, > - int write, int force, struct page **pages, > + unsigned int gup_flags, struct page **pages, > struct vm_area_struct **vmas); > long get_user_pages(unsigned long start, unsigned long nr_pages, > unsigned int gup_flags, struct page **pages, > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index d4129bb..f9ec9ad 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -300,7 +300,8 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, > > retry: > /* Read the page with vaddr into memory */ > - ret = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); > + ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page, > + &vma); > if (ret <= 0) > return ret; > > @@ -1710,7 +1711,8 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) > * but we treat this as a 'remote' access since it is > * essentially a kernel access to the memory. > */ > - result = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &page, NULL); > + result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page, > + NULL); > if (result < 0) > return result; > > diff --git a/mm/gup.c b/mm/gup.c > index dc91303..0deecf3 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -905,9 +905,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked); > * @mm: mm_struct of target mm > * @start: starting user address > * @nr_pages: number of pages from start to pin > - * @write: whether pages will be written to by the caller > - * @force: whether to force access even when user mapping is currently > - * protected (but never forces write access to shared mapping). > + * @gup_flags: flags modifying lookup behaviour > * @pages: array that receives pointers to the pages pinned. > * Should be at least nr_pages long. Or NULL, if caller > * only intends to ensure the pages are faulted in. > @@ -936,9 +934,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked); > * or similar operation cannot guarantee anything stronger anyway because > * locks can't be held over the syscall boundary. > * > - * If write=0, the page must not be written to. If the page is written to, > - * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called > - * after the page is finished with, and before put_page is called. > + * If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page > + * is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must > + * be called after the page is finished with, and before put_page is called. > * > * get_user_pages is typically used for fewer-copy IO operations, to get a > * handle on the memory by some means other than accesses via the user virtual > @@ -955,18 +953,12 @@ EXPORT_SYMBOL(get_user_pages_unlocked); > */ > long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, > unsigned long start, unsigned long nr_pages, > - int write, int force, struct page **pages, > + unsigned int gup_flags, struct page **pages, > struct vm_area_struct **vmas) > { > - unsigned int flags = FOLL_TOUCH | FOLL_REMOTE; > - > - if (write) > - flags |= FOLL_WRITE; > - if (force) > - flags |= FOLL_FORCE; > - > return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas, > - NULL, false, flags); > + NULL, false, > + gup_flags | FOLL_TOUCH | FOLL_REMOTE); > } > EXPORT_SYMBOL(get_user_pages_remote); > > diff --git a/mm/memory.c b/mm/memory.c > index fc1987d..20a9adb 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3873,6 +3873,10 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, > { > struct vm_area_struct *vma; > void *old_buf = buf; > + unsigned int flags = FOLL_FORCE; > + > + if (write) > + flags |= FOLL_WRITE; > > down_read(&mm->mmap_sem); > /* ignore errors, just check how much was successfully transferred */ > @@ -3882,7 +3886,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, > struct page *page = NULL; > > ret = get_user_pages_remote(tsk, mm, addr, 1, > - write, 1, &page, &vma); > + flags, &page, &vma); > if (ret <= 0) { > #ifndef CONFIG_HAVE_IOREMAP_PROT > break; > diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c > index ade7c6c..682b73a 100644 > --- a/security/tomoyo/domain.c > +++ b/security/tomoyo/domain.c > @@ -881,7 +881,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos, > * the execve(). > */ > if (get_user_pages_remote(current, bprm->mm, pos, 1, > - 0, 1, &page, NULL) <= 0) > + FOLL_FORCE, &page, NULL) <= 0) > return false; > #else > page = bprm->page[pos / PAGE_SIZE]; > -- > 2.10.0 > -- Jan Kara SUSE Labs, CR