[PATCH 02/10] mm: remove write/force parameters from __get_user_pages_unlocked()
From: Lorenzo Stoakes <hidden>
Date: 2016-10-13 00:20:12
Also in:
ceph-devel, dri-devel, intel-gfx, kvm, linux-alpha, linux-arm-kernel, linux-fsdevel, linux-media, linux-mips, linux-mm, linux-rdma, linux-s390, linux-samsung-soc, linux-scsi, linux-sh, linuxppc-dev, lkml, netdev, sparclinux
Subsystem:
kernel virtual machine (kvm), memory management, memory management - core, memory management - gup (get user pages), memory management - misc, memory mapping, the rest · Maintainers:
Paolo Bonzini, Andrew Morton, David Hildenbrand, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds
This patch removes the write and force parameters from __get_user_pages_unlocked() 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 <redacted> --- include/linux/mm.h | 3 +-- mm/gup.c | 17 +++++++++-------- mm/nommu.c | 12 +++++++++--- mm/process_vm_access.c | 7 +++++-- virt/kvm/async_pf.c | 3 ++- virt/kvm/kvm_main.c | 11 ++++++++--- 6 files changed, 34 insertions(+), 19 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e9caec6..2db98b6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -1285,8 +1285,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, int *locked); long __get_user_pages_unlocked(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, unsigned int gup_flags); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages); int get_user_pages_fast(unsigned long start, int nr_pages, int write,
diff --git a/mm/gup.c b/mm/gup.c
index ba83942..3d620dd 100644
--- a/mm/gup.c
+++ b/mm/gup.c@@ -865,17 +865,11 @@ EXPORT_SYMBOL(get_user_pages_locked); */ __always_inline long __get_user_pages_unlocked(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, unsigned int gup_flags) { long ret; int locked = 1; - if (write) - gup_flags |= FOLL_WRITE; - if (force) - gup_flags |= FOLL_FORCE; - down_read(&mm->mmap_sem); ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL, &locked, false, gup_flags);
@@ -905,8 +899,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) { + unsigned int flags = FOLL_TOUCH; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + return __get_user_pages_unlocked(current, current->mm, start, nr_pages, - write, force, pages, FOLL_TOUCH); + pages, flags); } EXPORT_SYMBOL(get_user_pages_unlocked);
diff --git a/mm/nommu.c b/mm/nommu.c
index 95daf81..925dcc1 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c@@ -185,8 +185,7 @@ EXPORT_SYMBOL(get_user_pages_locked); long __get_user_pages_unlocked(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, unsigned int gup_flags) { long ret; down_read(&mm->mmap_sem);
@@ -200,8 +199,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) { + unsigned int flags = 0; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + return __get_user_pages_unlocked(current, current->mm, start, nr_pages, - write, force, pages, 0); + pages, flags); } EXPORT_SYMBOL(get_user_pages_unlocked);
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 07514d4..be8dc8d 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c@@ -88,12 +88,16 @@ static int process_vm_rw_single_vec(unsigned long addr, ssize_t rc = 0; unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES / sizeof(struct pages *); + unsigned int flags = FOLL_REMOTE; /* Work out address and page range required */ if (len = 0) return 0; nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1; + if (vm_write) + flags |= FOLL_WRITE; + while (!rc && nr_pages && iov_iter_count(iter)) { int pages = min(nr_pages, max_pages_per_loop); size_t bytes;
@@ -104,8 +108,7 @@ static int process_vm_rw_single_vec(unsigned long addr, * current/current->mm */ pages = __get_user_pages_unlocked(task, mm, pa, pages, - vm_write, 0, process_pages, - FOLL_REMOTE); + process_pages, flags); if (pages <= 0) return -EFAULT;
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index db96688..8035cc1 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c@@ -84,7 +84,8 @@ static void async_pf_execute(struct work_struct *work) * mm and might be done in another context, so we must * use FOLL_REMOTE. */ - __get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL, FOLL_REMOTE); + __get_user_pages_unlocked(NULL, mm, addr, 1, NULL, + FOLL_WRITE | FOLL_REMOTE); kvm_async_page_present_sync(vcpu, apf);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 81dfc73..28510e7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -1416,10 +1416,15 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, down_read(¤t->mm->mmap_sem); npages = get_user_page_nowait(addr, write_fault, page); up_read(¤t->mm->mmap_sem); - } else + } else { + unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON; + + if (write_fault) + flags |= FOLL_WRITE; + npages = __get_user_pages_unlocked(current, current->mm, addr, 1, - write_fault, 0, page, - FOLL_TOUCH|FOLL_HWPOISON); + page, flags); + } if (npages != 1) return npages;
--
2.10.0