* [PATCH v2 1/2] mm: add locked parameter to get_user_pages_remote()
2016-10-27 20:34 [PATCH v2 0/2] mm: unexport __get_user_pages_unlocked() Lorenzo Stoakes
@ 2016-10-27 20:34 ` Lorenzo Stoakes
2016-10-27 20:34 ` [PATCH v2 2/2] mm: unexport __get_user_pages_unlocked() Lorenzo Stoakes
1 sibling, 0 replies; 3+ messages in thread
From: Lorenzo Stoakes @ 2016-10-27 20:34 UTC (permalink / raw)
To: linux-mm
Cc: Michal Hocko, Linus Torvalds, Jan Kara, Hugh Dickins, Dave Hansen,
Rik van Riel, Mel Gorman, Andrew Morton, Paolo Bonzini,
Radim Krčmář, kvm, linux-kernel,
linux-security-module, linux-rdma, dri-devel, linux-fsdevel,
Lorenzo Stoakes
This patch adds an int *locked parameter to get_user_pages_remote() to allow
VM_FAULT_RETRY faulting behaviour similar to get_user_pages_[un]locked().
It additionally clears the way for __get_user_pages_unlocked() to be unexported
as its sole remaining useful characteristic was to allow for VM_FAULT_RETRY
behaviour when faulting in pages.
It should not introduce any functional changes, however it does allow for
subsequent changes to get_user_pages_remote() callers to take advantage of
VM_FAULT_RETRY.
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
---
v2: updated description
drivers/gpu/drm/etnaviv/etnaviv_gem.c | 2 +-
drivers/gpu/drm/i915/i915_gem_userptr.c | 2 +-
drivers/infiniband/core/umem_odp.c | 2 +-
fs/exec.c | 2 +-
include/linux/mm.h | 2 +-
kernel/events/uprobes.c | 4 ++--
mm/gup.c | 12 ++++++++----
mm/memory.c | 2 +-
security/tomoyo/domain.c | 2 +-
9 files changed, 17 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 0370b84..0c69a97f 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -763,7 +763,7 @@ static struct page **etnaviv_gem_userptr_do_get_pages(
down_read(&mm->mmap_sem);
while (pinned < npages) {
ret = get_user_pages_remote(task, mm, ptr, npages - pinned,
- flags, pvec + pinned, NULL);
+ flags, pvec + pinned, NULL, 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 c6f780f..836b525 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -522,7 +522,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
obj->userptr.ptr + pinned * PAGE_SIZE,
npages - pinned,
flags,
- pvec + pinned, NULL);
+ pvec + pinned, NULL, NULL);
if (ret < 0)
break;
diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 1f0fe32..6b079a3 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -578,7 +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,
- flags, local_page_list, NULL);
+ flags, local_page_list, NULL, NULL);
up_read(&owning_mm->mmap_sem);
if (npages < 0)
diff --git a/fs/exec.c b/fs/exec.c
index 4e497b9..2cf049d 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -209,7 +209,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
* doing the exec and bprm->mm is the new process's mm.
*/
ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
- &page, NULL);
+ &page, NULL, NULL);
if (ret <= 0)
return NULL;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a92c8d7..cc15445 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1274,7 +1274,7 @@ extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas);
+ struct vm_area_struct **vmas, int *locked);
long get_user_pages(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
struct vm_area_struct **vmas);
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f9ec9ad..215871b 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -301,7 +301,7 @@ 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, FOLL_FORCE, &old_page,
- &vma);
+ &vma, NULL);
if (ret <= 0)
return ret;
@@ -1712,7 +1712,7 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
* essentially a kernel access to the memory.
*/
result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page,
- NULL);
+ NULL, NULL);
if (result < 0)
return result;
diff --git a/mm/gup.c b/mm/gup.c
index ec4f827..0567851 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -920,6 +920,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
* only intends to ensure the pages are faulted in.
* @vmas: array of pointers to vmas corresponding to each page.
* Or NULL if the caller does not require them.
+ * @locked: pointer to lock flag indicating whether lock is held and
+ * subsequently whether VM_FAULT_RETRY functionality can be
+ * utilised. Lock must initially be held.
*
* Returns number of pages pinned. This may be fewer than the number
* requested. If nr_pages is 0 or negative, returns 0. If no pages
@@ -963,10 +966,10 @@ 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,
unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas)
+ struct vm_area_struct **vmas, int *locked)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
- NULL, false,
+ locked, true,
gup_flags | FOLL_TOUCH | FOLL_REMOTE);
}
EXPORT_SYMBOL(get_user_pages_remote);
@@ -974,8 +977,9 @@ EXPORT_SYMBOL(get_user_pages_remote);
/*
* This is the same as get_user_pages_remote(), just with a
* less-flexible calling convention where we assume that the task
- * and mm being operated on are the current task's. We also
- * obviously don't pass FOLL_REMOTE in here.
+ * and mm being operated on are the current task's and don't allow
+ * passing of a locked parameter. We also obviously don't pass
+ * FOLL_REMOTE in here.
*/
long get_user_pages(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
diff --git a/mm/memory.c b/mm/memory.c
index e18c57b..2f3949b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3883,7 +3883,7 @@ 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,
- gup_flags, &page, &vma);
+ gup_flags, &page, &vma, NULL);
if (ret <= 0) {
#ifndef CONFIG_HAVE_IOREMAP_PROT
break;
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 682b73a..838ffa7 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,
- FOLL_FORCE, &page, NULL) <= 0)
+ FOLL_FORCE, &page, NULL, NULL) <= 0)
return false;
#else
page = bprm->page[pos / PAGE_SIZE];
--
2.10.1
--
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^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v2 2/2] mm: unexport __get_user_pages_unlocked()
2016-10-27 20:34 [PATCH v2 0/2] mm: unexport __get_user_pages_unlocked() Lorenzo Stoakes
2016-10-27 20:34 ` [PATCH v2 1/2] mm: add locked parameter to get_user_pages_remote() Lorenzo Stoakes
@ 2016-10-27 20:34 ` Lorenzo Stoakes
1 sibling, 0 replies; 3+ messages in thread
From: Lorenzo Stoakes @ 2016-10-27 20:34 UTC (permalink / raw)
To: linux-mm
Cc: Michal Hocko, Linus Torvalds, Jan Kara, Hugh Dickins, Dave Hansen,
Rik van Riel, Mel Gorman, Andrew Morton, Paolo Bonzini,
Radim Krčmář, kvm, linux-kernel,
linux-security-module, linux-rdma, dri-devel, linux-fsdevel,
Lorenzo Stoakes
This patch unexports the low-level __get_user_pages_unlocked() function and
replaces invocations with calls to more appropriate higher-level functions.
In hva_to_pfn_slow() we are able to replace __get_user_pages_unlocked() with
get_user_pages_unlocked() since we can now pass gup_flags.
In async_pf_execute() and process_vm_rw_single_vec() we need to pass different
tsk, mm arguments so get_user_pages_remote() is the sane replacement in these
cases (having added manual acquisition and release of mmap_sem.)
Additionally get_user_pages_remote() reintroduces use of the FOLL_TOUCH
flag. However, this flag was originally silently dropped by 1e9877902dc7e
("mm/gup: Introduce get_user_pages_remote()"), so this appears to have been
unintentional and reintroducing it is therefore not an issue.
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
---
v2: updated patch to apply against mainline rather than -mmots
include/linux/mm.h | 3 ---
mm/gup.c | 8 ++++----
mm/nommu.c | 7 +++----
mm/process_vm_access.c | 12 ++++++++----
virt/kvm/async_pf.c | 10 +++++++---
virt/kvm/kvm_main.c | 5 ++---
6 files changed, 24 insertions(+), 21 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index cc15445..7b2d14e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1280,9 +1280,6 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
struct vm_area_struct **vmas);
long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, 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,
- struct page **pages, unsigned int gup_flags);
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags);
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
diff --git a/mm/gup.c b/mm/gup.c
index 0567851..8028af1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -866,9 +866,10 @@ EXPORT_SYMBOL(get_user_pages_locked);
* according to the parameters "pages", "write", "force"
* respectively.
*/
-__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
- unsigned long start, unsigned long nr_pages,
- struct page **pages, unsigned int gup_flags)
+static __always_inline long __get_user_pages_unlocked(struct task_struct *tsk,
+ struct mm_struct *mm, unsigned long start,
+ unsigned long nr_pages, struct page **pages,
+ unsigned int gup_flags)
{
long ret;
int locked = 1;
@@ -880,7 +881,6 @@ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m
up_read(&mm->mmap_sem);
return ret;
}
-EXPORT_SYMBOL(__get_user_pages_unlocked);
/*
* get_user_pages_unlocked() is suitable to replace the form:
diff --git a/mm/nommu.c b/mm/nommu.c
index 8b8faaf..669437b 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -176,9 +176,9 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
}
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,
- struct page **pages, unsigned int gup_flags)
+static long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long start, unsigned long nr_pages,
+ struct page **pages, unsigned int gup_flags)
{
long ret;
down_read(&mm->mmap_sem);
@@ -187,7 +187,6 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
up_read(&mm->mmap_sem);
return ret;
}
-EXPORT_SYMBOL(__get_user_pages_unlocked);
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags)
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index be8dc8d..84d0c7e 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -88,7 +88,7 @@ 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;
+ unsigned int flags = 0;
/* Work out address and page range required */
if (len == 0)
@@ -100,15 +100,19 @@ static int process_vm_rw_single_vec(unsigned long addr,
while (!rc && nr_pages && iov_iter_count(iter)) {
int pages = min(nr_pages, max_pages_per_loop);
+ int locked = 1;
size_t bytes;
/*
* Get the pages we're interested in. We must
- * add FOLL_REMOTE because task/mm might not
+ * access remotely because task/mm might not
* current/current->mm
*/
- pages = __get_user_pages_unlocked(task, mm, pa, pages,
- process_pages, flags);
+ down_read(&mm->mmap_sem);
+ pages = get_user_pages_remote(task, mm, pa, pages, flags,
+ process_pages, NULL, &locked);
+ if (locked)
+ up_read(&mm->mmap_sem);
if (pages <= 0)
return -EFAULT;
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 8035cc1..dab8b19 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -76,16 +76,20 @@ static void async_pf_execute(struct work_struct *work)
struct kvm_vcpu *vcpu = apf->vcpu;
unsigned long addr = apf->addr;
gva_t gva = apf->gva;
+ int locked = 1;
might_sleep();
/*
* This work is run asynchromously to the task which owns
* mm and might be done in another context, so we must
- * use FOLL_REMOTE.
+ * access remotely.
*/
- __get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
- FOLL_WRITE | FOLL_REMOTE);
+ down_read(&mm->mmap_sem);
+ get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
+ &locked);
+ if (locked)
+ up_read(&mm->mmap_sem);
kvm_async_page_present_sync(vcpu, apf);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2907b7b..c45d951 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1415,13 +1415,12 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
npages = get_user_page_nowait(addr, write_fault, page);
up_read(¤t->mm->mmap_sem);
} else {
- unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON;
+ unsigned int flags = FOLL_HWPOISON;
if (write_fault)
flags |= FOLL_WRITE;
- npages = __get_user_pages_unlocked(current, current->mm, addr, 1,
- page, flags);
+ npages = get_user_pages_unlocked(addr, 1, page, flags);
}
if (npages != 1)
return npages;
--
2.10.1
--
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^ permalink raw reply related [flat|nested] 3+ messages in thread