linux/drivers/infiniband/core/umem_odp.c
Lorenzo Stoakes 5b56d49fc3 mm: add locked parameter to get_user_pages_remote()
Patch series "mm: unexport __get_user_pages_unlocked()".

This patch series continues the cleanup of get_user_pages*() functions
taking advantage of the fact we can now pass gup_flags as we please.

It firstly adds an additional 'locked' parameter to
get_user_pages_remote() to allow for its callers to utilise
VM_FAULT_RETRY functionality.  This is necessary as the invocation of
__get_user_pages_unlocked() in process_vm_rw_single_vec() makes use of
this and no other existing higher level function would allow it to do
so.

Secondly existing callers of __get_user_pages_unlocked() are replaced
with the appropriate higher-level replacement -
get_user_pages_unlocked() if the current task and memory descriptor are
referenced, or get_user_pages_remote() if other task/memory descriptors
are referenced (having acquiring mmap_sem.)

This patch (of 2):

Add a int *locked parameter to get_user_pages_remote() to allow
VM_FAULT_RETRY faulting behaviour similar to get_user_pages_[un]locked().

Taking into account the previous adjustments to get_user_pages*()
functions allowing for the passing of gup_flags, we are now in a
position where __get_user_pages_unlocked() need only be exported for his
ability to allow VM_FAULT_RETRY behaviour, this adjustment allows us to
subsequently unexport __get_user_pages_unlocked() as well as allowing
for future flexibility in the use of get_user_pages_remote().

[sfr@canb.auug.org.au: merge fix for get_user_pages_remote API change]
  Link: http://lkml.kernel.org/r/20161122210511.024ec341@canb.auug.org.au
Link: http://lkml.kernel.org/r/20161027095141.2569-2-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-14 16:04:08 -08:00

673 lines
20 KiB
C

/*
* Copyright (c) 2014 Mellanox Technologies. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/pid.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/vmalloc.h>
#include <rdma/ib_verbs.h>
#include <rdma/ib_umem.h>
#include <rdma/ib_umem_odp.h>
static void ib_umem_notifier_start_account(struct ib_umem *item)
{
mutex_lock(&item->odp_data->umem_mutex);
/* Only update private counters for this umem if it has them.
* Otherwise skip it. All page faults will be delayed for this umem. */
if (item->odp_data->mn_counters_active) {
int notifiers_count = item->odp_data->notifiers_count++;
if (notifiers_count == 0)
/* Initialize the completion object for waiting on
* notifiers. Since notifier_count is zero, no one
* should be waiting right now. */
reinit_completion(&item->odp_data->notifier_completion);
}
mutex_unlock(&item->odp_data->umem_mutex);
}
static void ib_umem_notifier_end_account(struct ib_umem *item)
{
mutex_lock(&item->odp_data->umem_mutex);
/* Only update private counters for this umem if it has them.
* Otherwise skip it. All page faults will be delayed for this umem. */
if (item->odp_data->mn_counters_active) {
/*
* This sequence increase will notify the QP page fault that
* the page that is going to be mapped in the spte could have
* been freed.
*/
++item->odp_data->notifiers_seq;
if (--item->odp_data->notifiers_count == 0)
complete_all(&item->odp_data->notifier_completion);
}
mutex_unlock(&item->odp_data->umem_mutex);
}
/* Account for a new mmu notifier in an ib_ucontext. */
static void ib_ucontext_notifier_start_account(struct ib_ucontext *context)
{
atomic_inc(&context->notifier_count);
}
/* Account for a terminating mmu notifier in an ib_ucontext.
*
* Must be called with the ib_ucontext->umem_rwsem semaphore unlocked, since
* the function takes the semaphore itself. */
static void ib_ucontext_notifier_end_account(struct ib_ucontext *context)
{
int zero_notifiers = atomic_dec_and_test(&context->notifier_count);
if (zero_notifiers &&
!list_empty(&context->no_private_counters)) {
/* No currently running mmu notifiers. Now is the chance to
* add private accounting to all previously added umems. */
struct ib_umem_odp *odp_data, *next;
/* Prevent concurrent mmu notifiers from working on the
* no_private_counters list. */
down_write(&context->umem_rwsem);
/* Read the notifier_count again, with the umem_rwsem
* semaphore taken for write. */
if (!atomic_read(&context->notifier_count)) {
list_for_each_entry_safe(odp_data, next,
&context->no_private_counters,
no_private_counters) {
mutex_lock(&odp_data->umem_mutex);
odp_data->mn_counters_active = true;
list_del(&odp_data->no_private_counters);
complete_all(&odp_data->notifier_completion);
mutex_unlock(&odp_data->umem_mutex);
}
}
up_write(&context->umem_rwsem);
}
}
static int ib_umem_notifier_release_trampoline(struct ib_umem *item, u64 start,
u64 end, void *cookie) {
/*
* Increase the number of notifiers running, to
* prevent any further fault handling on this MR.
*/
ib_umem_notifier_start_account(item);
item->odp_data->dying = 1;
/* Make sure that the fact the umem is dying is out before we release
* all pending page faults. */
smp_wmb();
complete_all(&item->odp_data->notifier_completion);
item->context->invalidate_range(item, ib_umem_start(item),
ib_umem_end(item));
return 0;
}
static void ib_umem_notifier_release(struct mmu_notifier *mn,
struct mm_struct *mm)
{
struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
if (!context->invalidate_range)
return;
ib_ucontext_notifier_start_account(context);
down_read(&context->umem_rwsem);
rbt_ib_umem_for_each_in_range(&context->umem_tree, 0,
ULLONG_MAX,
ib_umem_notifier_release_trampoline,
NULL);
up_read(&context->umem_rwsem);
}
static int invalidate_page_trampoline(struct ib_umem *item, u64 start,
u64 end, void *cookie)
{
ib_umem_notifier_start_account(item);
item->context->invalidate_range(item, start, start + PAGE_SIZE);
ib_umem_notifier_end_account(item);
return 0;
}
static void ib_umem_notifier_invalidate_page(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long address)
{
struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
if (!context->invalidate_range)
return;
ib_ucontext_notifier_start_account(context);
down_read(&context->umem_rwsem);
rbt_ib_umem_for_each_in_range(&context->umem_tree, address,
address + PAGE_SIZE,
invalidate_page_trampoline, NULL);
up_read(&context->umem_rwsem);
ib_ucontext_notifier_end_account(context);
}
static int invalidate_range_start_trampoline(struct ib_umem *item, u64 start,
u64 end, void *cookie)
{
ib_umem_notifier_start_account(item);
item->context->invalidate_range(item, start, end);
return 0;
}
static void ib_umem_notifier_invalidate_range_start(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
if (!context->invalidate_range)
return;
ib_ucontext_notifier_start_account(context);
down_read(&context->umem_rwsem);
rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
end,
invalidate_range_start_trampoline, NULL);
up_read(&context->umem_rwsem);
}
static int invalidate_range_end_trampoline(struct ib_umem *item, u64 start,
u64 end, void *cookie)
{
ib_umem_notifier_end_account(item);
return 0;
}
static void ib_umem_notifier_invalidate_range_end(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
if (!context->invalidate_range)
return;
down_read(&context->umem_rwsem);
rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
end,
invalidate_range_end_trampoline, NULL);
up_read(&context->umem_rwsem);
ib_ucontext_notifier_end_account(context);
}
static const struct mmu_notifier_ops ib_umem_notifiers = {
.release = ib_umem_notifier_release,
.invalidate_page = ib_umem_notifier_invalidate_page,
.invalidate_range_start = ib_umem_notifier_invalidate_range_start,
.invalidate_range_end = ib_umem_notifier_invalidate_range_end,
};
int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem)
{
int ret_val;
struct pid *our_pid;
struct mm_struct *mm = get_task_mm(current);
if (!mm)
return -EINVAL;
/* Prevent creating ODP MRs in child processes */
rcu_read_lock();
our_pid = get_task_pid(current->group_leader, PIDTYPE_PID);
rcu_read_unlock();
put_pid(our_pid);
if (context->tgid != our_pid) {
ret_val = -EINVAL;
goto out_mm;
}
umem->hugetlb = 0;
umem->odp_data = kzalloc(sizeof(*umem->odp_data), GFP_KERNEL);
if (!umem->odp_data) {
ret_val = -ENOMEM;
goto out_mm;
}
umem->odp_data->umem = umem;
mutex_init(&umem->odp_data->umem_mutex);
init_completion(&umem->odp_data->notifier_completion);
umem->odp_data->page_list = vzalloc(ib_umem_num_pages(umem) *
sizeof(*umem->odp_data->page_list));
if (!umem->odp_data->page_list) {
ret_val = -ENOMEM;
goto out_odp_data;
}
umem->odp_data->dma_list = vzalloc(ib_umem_num_pages(umem) *
sizeof(*umem->odp_data->dma_list));
if (!umem->odp_data->dma_list) {
ret_val = -ENOMEM;
goto out_page_list;
}
/*
* When using MMU notifiers, we will get a
* notification before the "current" task (and MM) is
* destroyed. We use the umem_rwsem semaphore to synchronize.
*/
down_write(&context->umem_rwsem);
context->odp_mrs_count++;
if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
rbt_ib_umem_insert(&umem->odp_data->interval_tree,
&context->umem_tree);
if (likely(!atomic_read(&context->notifier_count)) ||
context->odp_mrs_count == 1)
umem->odp_data->mn_counters_active = true;
else
list_add(&umem->odp_data->no_private_counters,
&context->no_private_counters);
downgrade_write(&context->umem_rwsem);
if (context->odp_mrs_count == 1) {
/*
* Note that at this point, no MMU notifier is running
* for this context!
*/
atomic_set(&context->notifier_count, 0);
INIT_HLIST_NODE(&context->mn.hlist);
context->mn.ops = &ib_umem_notifiers;
/*
* Lock-dep detects a false positive for mmap_sem vs.
* umem_rwsem, due to not grasping downgrade_write correctly.
*/
lockdep_off();
ret_val = mmu_notifier_register(&context->mn, mm);
lockdep_on();
if (ret_val) {
pr_err("Failed to register mmu_notifier %d\n", ret_val);
ret_val = -EBUSY;
goto out_mutex;
}
}
up_read(&context->umem_rwsem);
/*
* Note that doing an mmput can cause a notifier for the relevant mm.
* If the notifier is called while we hold the umem_rwsem, this will
* cause a deadlock. Therefore, we release the reference only after we
* released the semaphore.
*/
mmput(mm);
return 0;
out_mutex:
up_read(&context->umem_rwsem);
vfree(umem->odp_data->dma_list);
out_page_list:
vfree(umem->odp_data->page_list);
out_odp_data:
kfree(umem->odp_data);
out_mm:
mmput(mm);
return ret_val;
}
void ib_umem_odp_release(struct ib_umem *umem)
{
struct ib_ucontext *context = umem->context;
/*
* Ensure that no more pages are mapped in the umem.
*
* It is the driver's responsibility to ensure, before calling us,
* that the hardware will not attempt to access the MR any more.
*/
ib_umem_odp_unmap_dma_pages(umem, ib_umem_start(umem),
ib_umem_end(umem));
down_write(&context->umem_rwsem);
if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
rbt_ib_umem_remove(&umem->odp_data->interval_tree,
&context->umem_tree);
context->odp_mrs_count--;
if (!umem->odp_data->mn_counters_active) {
list_del(&umem->odp_data->no_private_counters);
complete_all(&umem->odp_data->notifier_completion);
}
/*
* Downgrade the lock to a read lock. This ensures that the notifiers
* (who lock the mutex for reading) will be able to finish, and we
* will be able to enventually obtain the mmu notifiers SRCU. Note
* that since we are doing it atomically, no other user could register
* and unregister while we do the check.
*/
downgrade_write(&context->umem_rwsem);
if (!context->odp_mrs_count) {
struct task_struct *owning_process = NULL;
struct mm_struct *owning_mm = NULL;
owning_process = get_pid_task(context->tgid,
PIDTYPE_PID);
if (owning_process == NULL)
/*
* The process is already dead, notifier were removed
* already.
*/
goto out;
owning_mm = get_task_mm(owning_process);
if (owning_mm == NULL)
/*
* The process' mm is already dead, notifier were
* removed already.
*/
goto out_put_task;
mmu_notifier_unregister(&context->mn, owning_mm);
mmput(owning_mm);
out_put_task:
put_task_struct(owning_process);
}
out:
up_read(&context->umem_rwsem);
vfree(umem->odp_data->dma_list);
vfree(umem->odp_data->page_list);
kfree(umem->odp_data);
kfree(umem);
}
/*
* Map for DMA and insert a single page into the on-demand paging page tables.
*
* @umem: the umem to insert the page to.
* @page_index: index in the umem to add the page to.
* @page: the page struct to map and add.
* @access_mask: access permissions needed for this page.
* @current_seq: sequence number for synchronization with invalidations.
* the sequence number is taken from
* umem->odp_data->notifiers_seq.
*
* The function returns -EFAULT if the DMA mapping operation fails. It returns
* -EAGAIN if a concurrent invalidation prevents us from updating the page.
*
* The page is released via put_page even if the operation failed. For
* on-demand pinning, the page is released whenever it isn't stored in the
* umem.
*/
static int ib_umem_odp_map_dma_single_page(
struct ib_umem *umem,
int page_index,
u64 base_virt_addr,
struct page *page,
u64 access_mask,
unsigned long current_seq)
{
struct ib_device *dev = umem->context->device;
dma_addr_t dma_addr;
int stored_page = 0;
int remove_existing_mapping = 0;
int ret = 0;
/*
* Note: we avoid writing if seq is different from the initial seq, to
* handle case of a racing notifier. This check also allows us to bail
* early if we have a notifier running in parallel with us.
*/
if (ib_umem_mmu_notifier_retry(umem, current_seq)) {
ret = -EAGAIN;
goto out;
}
if (!(umem->odp_data->dma_list[page_index])) {
dma_addr = ib_dma_map_page(dev,
page,
0, PAGE_SIZE,
DMA_BIDIRECTIONAL);
if (ib_dma_mapping_error(dev, dma_addr)) {
ret = -EFAULT;
goto out;
}
umem->odp_data->dma_list[page_index] = dma_addr | access_mask;
umem->odp_data->page_list[page_index] = page;
stored_page = 1;
} else if (umem->odp_data->page_list[page_index] == page) {
umem->odp_data->dma_list[page_index] |= access_mask;
} else {
pr_err("error: got different pages in IB device and from get_user_pages. IB device page: %p, gup page: %p\n",
umem->odp_data->page_list[page_index], page);
/* Better remove the mapping now, to prevent any further
* damage. */
remove_existing_mapping = 1;
}
out:
/* On Demand Paging - avoid pinning the page */
if (umem->context->invalidate_range || !stored_page)
put_page(page);
if (remove_existing_mapping && umem->context->invalidate_range) {
invalidate_page_trampoline(
umem,
base_virt_addr + (page_index * PAGE_SIZE),
base_virt_addr + ((page_index+1)*PAGE_SIZE),
NULL);
ret = -EAGAIN;
}
return ret;
}
/**
* ib_umem_odp_map_dma_pages - Pin and DMA map userspace memory in an ODP MR.
*
* Pins the range of pages passed in the argument, and maps them to
* DMA addresses. The DMA addresses of the mapped pages is updated in
* umem->odp_data->dma_list.
*
* Returns the number of pages mapped in success, negative error code
* for failure.
* An -EAGAIN error code is returned when a concurrent mmu notifier prevents
* the function from completing its task.
*
* @umem: the umem to map and pin
* @user_virt: the address from which we need to map.
* @bcnt: the minimal number of bytes to pin and map. The mapping might be
* bigger due to alignment, and may also be smaller in case of an error
* pinning or mapping a page. The actual pages mapped is returned in
* the return value.
* @access_mask: bit mask of the requested access permissions for the given
* range.
* @current_seq: the MMU notifiers sequance value for synchronization with
* invalidations. the sequance number is read from
* umem->odp_data->notifiers_seq before calling this function
*/
int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
u64 access_mask, unsigned long current_seq)
{
struct task_struct *owning_process = NULL;
struct mm_struct *owning_mm = NULL;
struct page **local_page_list = NULL;
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;
if (user_virt < ib_umem_start(umem) ||
user_virt + bcnt > ib_umem_end(umem))
return -EFAULT;
local_page_list = (struct page **)__get_free_page(GFP_KERNEL);
if (!local_page_list)
return -ENOMEM;
off = user_virt & (~PAGE_MASK);
user_virt = user_virt & PAGE_MASK;
base_virt_addr = user_virt;
bcnt += off; /* Charge for the first page offset as well. */
owning_process = get_pid_task(umem->context->tgid, PIDTYPE_PID);
if (owning_process == NULL) {
ret = -EINVAL;
goto out_no_task;
}
owning_mm = get_task_mm(owning_process);
if (owning_mm == NULL) {
ret = -EINVAL;
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;
while (bcnt > 0) {
const size_t gup_num_pages =
min_t(size_t, ALIGN(bcnt, PAGE_SIZE) / PAGE_SIZE,
PAGE_SIZE / sizeof(struct page *));
down_read(&owning_mm->mmap_sem);
/*
* Note: this might result in redundent page getting. We can
* avoid this by checking dma_list to be 0 before calling
* get_user_pages. However, this make the code much more
* complex (and doesn't gain us much performance in most use
* cases).
*/
npages = get_user_pages_remote(owning_process, owning_mm,
user_virt, gup_num_pages,
flags, local_page_list, NULL, NULL);
up_read(&owning_mm->mmap_sem);
if (npages < 0)
break;
bcnt -= min_t(size_t, npages << PAGE_SHIFT, bcnt);
user_virt += npages << PAGE_SHIFT;
mutex_lock(&umem->odp_data->umem_mutex);
for (j = 0; j < npages; ++j) {
ret = ib_umem_odp_map_dma_single_page(
umem, k, base_virt_addr, local_page_list[j],
access_mask, current_seq);
if (ret < 0)
break;
k++;
}
mutex_unlock(&umem->odp_data->umem_mutex);
if (ret < 0) {
/* Release left over pages when handling errors. */
for (++j; j < npages; ++j)
put_page(local_page_list[j]);
break;
}
}
if (ret >= 0) {
if (npages < 0 && k == start_idx)
ret = npages;
else
ret = k - start_idx;
}
mmput(owning_mm);
out_put_task:
put_task_struct(owning_process);
out_no_task:
free_page((unsigned long)local_page_list);
return ret;
}
EXPORT_SYMBOL(ib_umem_odp_map_dma_pages);
void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 virt,
u64 bound)
{
int idx;
u64 addr;
struct ib_device *dev = umem->context->device;
virt = max_t(u64, virt, ib_umem_start(umem));
bound = min_t(u64, bound, ib_umem_end(umem));
/* Note that during the run of this function, the
* notifiers_count of the MR is > 0, preventing any racing
* faults from completion. We might be racing with other
* invalidations, so we must make sure we free each page only
* once. */
mutex_lock(&umem->odp_data->umem_mutex);
for (addr = virt; addr < bound; addr += (u64)umem->page_size) {
idx = (addr - ib_umem_start(umem)) / PAGE_SIZE;
if (umem->odp_data->page_list[idx]) {
struct page *page = umem->odp_data->page_list[idx];
dma_addr_t dma = umem->odp_data->dma_list[idx];
dma_addr_t dma_addr = dma & ODP_DMA_ADDR_MASK;
WARN_ON(!dma_addr);
ib_dma_unmap_page(dev, dma_addr, PAGE_SIZE,
DMA_BIDIRECTIONAL);
if (dma & ODP_WRITE_ALLOWED_BIT) {
struct page *head_page = compound_head(page);
/*
* set_page_dirty prefers being called with
* the page lock. However, MMU notifiers are
* called sometimes with and sometimes without
* the lock. We rely on the umem_mutex instead
* to prevent other mmu notifiers from
* continuing and allowing the page mapping to
* be removed.
*/
set_page_dirty(head_page);
}
/* on demand pinning support */
if (!umem->context->invalidate_range)
put_page(page);
umem->odp_data->page_list[idx] = NULL;
umem->odp_data->dma_list[idx] = 0;
}
}
mutex_unlock(&umem->odp_data->umem_mutex);
}
EXPORT_SYMBOL(ib_umem_odp_unmap_dma_pages);