Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752187AbbG0HCL (ORCPT ); Mon, 27 Jul 2015 03:02:11 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:38250 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751244AbbG0HCI (ORCPT ); Mon, 27 Jul 2015 03:02:08 -0400 Date: Mon, 27 Jul 2015 10:02:04 +0300 From: "Kirill A. Shutemov" To: Eric B Munson Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Jonathan Corbet , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-api@vger.kernel.org Subject: Re: [PATCH V5 3/7] mm: Introduce VM_LOCKONFAULT Message-ID: <20150727070204.GC11657@node.dhcp.inet.fi> References: <1437773325-8623-1-git-send-email-emunson@akamai.com> <1437773325-8623-4-git-send-email-emunson@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437773325-8623-4-git-send-email-emunson@akamai.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7881 Lines: 194 On Fri, Jul 24, 2015 at 05:28:41PM -0400, Eric B Munson wrote: > The cost of faulting in all memory to be locked can be very high when > working with large mappings. If only portions of the mapping will be > used this can incur a high penalty for locking. > > For the example of a large file, this is the usage pattern for a large > statical language model (probably applies to other statical or graphical > models as well). For the security example, any application transacting > in data that cannot be swapped out (credit card data, medical records, > etc). > > This patch introduces the ability to request that pages are not > pre-faulted, but are placed on the unevictable LRU when they are finally > faulted in. The VM_LOCKONFAULT flag will be used together with > VM_LOCKED and has no effect when set without VM_LOCKED. Setting the > VM_LOCKONFAULT flag for a VMA will cause pages faulted into that VMA to > be added to the unevictable LRU when they are faulted or if they are > already present, but will not cause any missing pages to be faulted in. > > Exposing this new lock state means that we cannot overload the meaning > of the FOLL_POPULATE flag any longer. Prior to this patch it was used > to mean that the VMA for a fault was locked. This means we need the > new FOLL_MLOCK flag to communicate the locked state of a VMA. > FOLL_POPULATE will now only control if the VMA should be populated and > in the case of VM_LOCKONFAULT, it will not be set. > > Signed-off-by: Eric B Munson > Cc: Michal Hocko > Cc: Vlastimil Babka > Cc: Jonathan Corbet > Cc: "Kirill A. Shutemov" > Cc: linux-kernel@vger.kernel.org > Cc: dri-devel@lists.freedesktop.org > Cc: linux-mm@kvack.org > Cc: linux-api@vger.kernel.org > --- > drivers/gpu/drm/drm_vm.c | 8 +++++++- > fs/proc/task_mmu.c | 1 + > include/linux/mm.h | 2 ++ > kernel/fork.c | 2 +- > mm/debug.c | 1 + > mm/gup.c | 10 ++++++++-- > mm/huge_memory.c | 2 +- > mm/hugetlb.c | 4 ++-- > mm/mlock.c | 2 +- > mm/mmap.c | 2 +- > mm/rmap.c | 4 ++-- > 11 files changed, 27 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c > index aab49ee..103a5f6 100644 > --- a/drivers/gpu/drm/drm_vm.c > +++ b/drivers/gpu/drm/drm_vm.c > @@ -699,9 +699,15 @@ int drm_vma_info(struct seq_file *m, void *data) > (void *)(unsigned long)virt_to_phys(high_memory)); > > list_for_each_entry(pt, &dev->vmalist, head) { > + char lock_flag = '-'; > + > vma = pt->vma; > if (!vma) > continue; > + if (vma->vm_flags & VM_LOCKONFAULT) > + lock_flag = 'f'; > + else if (vma->vm_flags & VM_LOCKED) > + lock_flag = 'l'; > seq_printf(m, > "\n%5d 0x%pK-0x%pK %c%c%c%c%c%c 0x%08lx000", > pt->pid, > @@ -710,7 +716,7 @@ int drm_vma_info(struct seq_file *m, void *data) > vma->vm_flags & VM_WRITE ? 'w' : '-', > vma->vm_flags & VM_EXEC ? 'x' : '-', > vma->vm_flags & VM_MAYSHARE ? 's' : 'p', > - vma->vm_flags & VM_LOCKED ? 'l' : '-', > + lock_flag, > vma->vm_flags & VM_IO ? 'i' : '-', > vma->vm_pgoff); > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index ca1e091..38d69fc 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -579,6 +579,7 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) > #ifdef CONFIG_X86_INTEL_MPX > [ilog2(VM_MPX)] = "mp", > #endif > + [ilog2(VM_LOCKONFAULT)] = "lf", > [ilog2(VM_LOCKED)] = "lo", > [ilog2(VM_IO)] = "io", > [ilog2(VM_SEQ_READ)] = "sr", > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 2e872f9..c2f3551 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -127,6 +127,7 @@ extern unsigned int kobjsize(const void *objp); > #define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */ > #define VM_DENYWRITE 0x00000800 /* ETXTBSY on write attempts.. */ > > +#define VM_LOCKONFAULT 0x00001000 /* Lock the pages covered when they are faulted in */ > #define VM_LOCKED 0x00002000 > #define VM_IO 0x00004000 /* Memory mapped I/O or similar */ > > @@ -2043,6 +2044,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma, > #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ > #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ > #define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */ > +#define FOLL_MLOCK 0x1000 /* lock present pages */ > > typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, > void *data); > diff --git a/kernel/fork.c b/kernel/fork.c > index dbd9b8d..a949228 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -454,7 +454,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) > tmp->vm_mm = mm; > if (anon_vma_fork(tmp, mpnt)) > goto fail_nomem_anon_vma_fork; > - tmp->vm_flags &= ~VM_LOCKED; > + tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT); > tmp->vm_next = tmp->vm_prev = NULL; > file = tmp->vm_file; > if (file) { > diff --git a/mm/debug.c b/mm/debug.c > index 76089dd..25176bb 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -121,6 +121,7 @@ static const struct trace_print_flags vmaflags_names[] = { > {VM_GROWSDOWN, "growsdown" }, > {VM_PFNMAP, "pfnmap" }, > {VM_DENYWRITE, "denywrite" }, > + {VM_LOCKONFAULT, "lockonfault" }, > {VM_LOCKED, "locked" }, > {VM_IO, "io" }, > {VM_SEQ_READ, "seqread" }, > diff --git a/mm/gup.c b/mm/gup.c > index 6297f6b..e632908 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -92,7 +92,7 @@ retry: > */ > mark_page_accessed(page); > } > - if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) { > + if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { > /* > * The preliminary mapping check is mainly to avoid the > * pointless overhead of lock_page on the ZERO_PAGE > @@ -265,6 +265,9 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma, > unsigned int fault_flags = 0; > int ret; > > + /* mlock all present pages, but do not fault in new pages */ > + if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK) > + return -ENOENT; > /* For mm_populate(), just skip the stack guard page. */ > if ((*flags & FOLL_POPULATE) && > (stack_guard_page_start(vma, address) || > @@ -850,7 +853,10 @@ long populate_vma_page_range(struct vm_area_struct *vma, > VM_BUG_ON_VMA(end > vma->vm_end, vma); > VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm); > > - gup_flags = FOLL_TOUCH | FOLL_POPULATE; > + gup_flags = FOLL_TOUCH | FOLL_MLOCK; > + if ((vma->vm_flags & (VM_LOCKED | VM_LOCKONFAULT)) == VM_LOCKED) > + gup_flags |= FOLL_POPULATE; > + > /* > * We want to touch writable mappings with a write fault in order > * to break COW, except for shared mappings because these don't COW > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index c107094..5e22d90 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1238,7 +1238,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, > pmd, _pmd, 1)) > update_mmu_cache_pmd(vma, addr, pmd); > } > - if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) { > + if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED )) { ^^^ Space befor ')'. Otherwise: Acked-by: Kirill A. Shutemov -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/