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-rw-r--r--fs/userfaultfd.c461
1 files changed, 437 insertions, 24 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 43953e03c356..18406158e13f 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -12,6 +12,7 @@
* mm/ksm.c (mm hashing).
*/
+#include <linux/list.h>
#include <linux/hashtable.h>
#include <linux/sched.h>
#include <linux/mm.h>
@@ -26,6 +27,7 @@
#include <linux/mempolicy.h>
#include <linux/ioctl.h>
#include <linux/security.h>
+#include <linux/hugetlb.h>
static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;
@@ -45,12 +47,16 @@ struct userfaultfd_ctx {
wait_queue_head_t fault_wqh;
/* waitqueue head for the pseudo fd to wakeup poll/read */
wait_queue_head_t fd_wqh;
+ /* waitqueue head for events */
+ wait_queue_head_t event_wqh;
/* a refile sequence protected by fault_pending_wqh lock */
struct seqcount refile_seq;
/* pseudo fd refcounting */
atomic_t refcount;
/* userfaultfd syscall flags */
unsigned int flags;
+ /* features requested from the userspace */
+ unsigned int features;
/* state machine */
enum userfaultfd_state state;
/* released */
@@ -59,6 +65,12 @@ struct userfaultfd_ctx {
struct mm_struct *mm;
};
+struct userfaultfd_fork_ctx {
+ struct userfaultfd_ctx *orig;
+ struct userfaultfd_ctx *new;
+ struct list_head list;
+};
+
struct userfaultfd_wait_queue {
struct uffd_msg msg;
wait_queue_t wq;
@@ -142,6 +154,8 @@ static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx)
VM_BUG_ON(waitqueue_active(&ctx->fault_pending_wqh));
VM_BUG_ON(spin_is_locked(&ctx->fault_wqh.lock));
VM_BUG_ON(waitqueue_active(&ctx->fault_wqh));
+ VM_BUG_ON(spin_is_locked(&ctx->event_wqh.lock));
+ VM_BUG_ON(waitqueue_active(&ctx->event_wqh));
VM_BUG_ON(spin_is_locked(&ctx->fd_wqh.lock));
VM_BUG_ON(waitqueue_active(&ctx->fd_wqh));
mmdrop(ctx->mm);
@@ -169,7 +183,7 @@ static inline struct uffd_msg userfault_msg(unsigned long address,
msg.arg.pagefault.address = address;
if (flags & FAULT_FLAG_WRITE)
/*
- * If UFFD_FEATURE_PAGEFAULT_FLAG_WRITE was set in the
+ * If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the
* uffdio_api.features and UFFD_PAGEFAULT_FLAG_WRITE
* was not set in a UFFD_EVENT_PAGEFAULT, it means it
* was a read fault, otherwise if set it means it's
@@ -188,6 +202,49 @@ static inline struct uffd_msg userfault_msg(unsigned long address,
return msg;
}
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * Same functionality as userfaultfd_must_wait below with modifications for
+ * hugepmd ranges.
+ */
+static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
+ unsigned long address,
+ unsigned long flags,
+ unsigned long reason)
+{
+ struct mm_struct *mm = ctx->mm;
+ pte_t *pte;
+ bool ret = true;
+
+ VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
+
+ pte = huge_pte_offset(mm, address);
+ if (!pte)
+ goto out;
+
+ ret = false;
+
+ /*
+ * Lockless access: we're in a wait_event so it's ok if it
+ * changes under us.
+ */
+ if (huge_pte_none(*pte))
+ ret = true;
+ if (!huge_pte_write(*pte) && (reason & VM_UFFD_WP))
+ ret = true;
+out:
+ return ret;
+}
+#else
+static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
+ unsigned long address,
+ unsigned long flags,
+ unsigned long reason)
+{
+ return false; /* should never get here */
+}
+#endif /* CONFIG_HUGETLB_PAGE */
+
/*
* Verify the pagetables are still not ok after having reigstered into
* the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any
@@ -364,8 +421,12 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
set_current_state(blocking_state);
spin_unlock(&ctx->fault_pending_wqh.lock);
- must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
- reason);
+ if (!is_vm_hugetlb_page(vmf->vma))
+ must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
+ reason);
+ else
+ must_wait = userfaultfd_huge_must_wait(ctx, vmf->address,
+ vmf->flags, reason);
up_read(&mm->mmap_sem);
if (likely(must_wait && !ACCESS_ONCE(ctx->released) &&
@@ -458,6 +519,196 @@ out:
return ret;
}
+static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
+ struct userfaultfd_wait_queue *ewq)
+{
+ int ret = 0;
+
+ ewq->ctx = ctx;
+ init_waitqueue_entry(&ewq->wq, current);
+
+ spin_lock(&ctx->event_wqh.lock);
+ /*
+ * After the __add_wait_queue the uwq is visible to userland
+ * through poll/read().
+ */
+ __add_wait_queue(&ctx->event_wqh, &ewq->wq);
+ for (;;) {
+ set_current_state(TASK_KILLABLE);
+ if (ewq->msg.event == 0)
+ break;
+ if (ACCESS_ONCE(ctx->released) ||
+ fatal_signal_pending(current)) {
+ ret = -1;
+ __remove_wait_queue(&ctx->event_wqh, &ewq->wq);
+ break;
+ }
+
+ spin_unlock(&ctx->event_wqh.lock);
+
+ wake_up_poll(&ctx->fd_wqh, POLLIN);
+ schedule();
+
+ spin_lock(&ctx->event_wqh.lock);
+ }
+ __set_current_state(TASK_RUNNING);
+ spin_unlock(&ctx->event_wqh.lock);
+
+ /*
+ * ctx may go away after this if the userfault pseudo fd is
+ * already released.
+ */
+
+ userfaultfd_ctx_put(ctx);
+ return ret;
+}
+
+static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx,
+ struct userfaultfd_wait_queue *ewq)
+{
+ ewq->msg.event = 0;
+ wake_up_locked(&ctx->event_wqh);
+ __remove_wait_queue(&ctx->event_wqh, &ewq->wq);
+}
+
+int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
+{
+ struct userfaultfd_ctx *ctx = NULL, *octx;
+ struct userfaultfd_fork_ctx *fctx;
+
+ octx = vma->vm_userfaultfd_ctx.ctx;
+ if (!octx || !(octx->features & UFFD_FEATURE_EVENT_FORK)) {
+ vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
+ vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
+ return 0;
+ }
+
+ list_for_each_entry(fctx, fcs, list)
+ if (fctx->orig == octx) {
+ ctx = fctx->new;
+ break;
+ }
+
+ if (!ctx) {
+ fctx = kmalloc(sizeof(*fctx), GFP_KERNEL);
+ if (!fctx)
+ return -ENOMEM;
+
+ ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL);
+ if (!ctx) {
+ kfree(fctx);
+ return -ENOMEM;
+ }
+
+ atomic_set(&ctx->refcount, 1);
+ ctx->flags = octx->flags;
+ ctx->state = UFFD_STATE_RUNNING;
+ ctx->features = octx->features;
+ ctx->released = false;
+ ctx->mm = vma->vm_mm;
+ atomic_inc(&ctx->mm->mm_count);
+
+ userfaultfd_ctx_get(octx);
+ fctx->orig = octx;
+ fctx->new = ctx;
+ list_add_tail(&fctx->list, fcs);
+ }
+
+ vma->vm_userfaultfd_ctx.ctx = ctx;
+ return 0;
+}
+
+static int dup_fctx(struct userfaultfd_fork_ctx *fctx)
+{
+ struct userfaultfd_ctx *ctx = fctx->orig;
+ struct userfaultfd_wait_queue ewq;
+
+ msg_init(&ewq.msg);
+
+ ewq.msg.event = UFFD_EVENT_FORK;
+ ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new;
+
+ return userfaultfd_event_wait_completion(ctx, &ewq);
+}
+
+void dup_userfaultfd_complete(struct list_head *fcs)
+{
+ int ret = 0;
+ struct userfaultfd_fork_ctx *fctx, *n;
+
+ list_for_each_entry_safe(fctx, n, fcs, list) {
+ if (!ret)
+ ret = dup_fctx(fctx);
+ list_del(&fctx->list);
+ kfree(fctx);
+ }
+}
+
+void mremap_userfaultfd_prep(struct vm_area_struct *vma,
+ struct vm_userfaultfd_ctx *vm_ctx)
+{
+ struct userfaultfd_ctx *ctx;
+
+ ctx = vma->vm_userfaultfd_ctx.ctx;
+ if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
+ vm_ctx->ctx = ctx;
+ userfaultfd_ctx_get(ctx);
+ }
+}
+
+void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx,
+ unsigned long from, unsigned long to,
+ unsigned long len)
+{
+ struct userfaultfd_ctx *ctx = vm_ctx->ctx;
+ struct userfaultfd_wait_queue ewq;
+
+ if (!ctx)
+ return;
+
+ if (to & ~PAGE_MASK) {
+ userfaultfd_ctx_put(ctx);
+ return;
+ }
+
+ msg_init(&ewq.msg);
+
+ ewq.msg.event = UFFD_EVENT_REMAP;
+ ewq.msg.arg.remap.from = from;
+ ewq.msg.arg.remap.to = to;
+ ewq.msg.arg.remap.len = len;
+
+ userfaultfd_event_wait_completion(ctx, &ewq);
+}
+
+void madvise_userfault_dontneed(struct vm_area_struct *vma,
+ struct vm_area_struct **prev,
+ unsigned long start, unsigned long end)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct userfaultfd_ctx *ctx;
+ struct userfaultfd_wait_queue ewq;
+
+ ctx = vma->vm_userfaultfd_ctx.ctx;
+ if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_MADVDONTNEED))
+ return;
+
+ userfaultfd_ctx_get(ctx);
+ up_read(&mm->mmap_sem);
+
+ *prev = NULL; /* We wait for ACK w/o the mmap semaphore */
+
+ msg_init(&ewq.msg);
+
+ ewq.msg.event = UFFD_EVENT_MADVDONTNEED;
+ ewq.msg.arg.madv_dn.start = start;
+ ewq.msg.arg.madv_dn.end = end;
+
+ userfaultfd_event_wait_completion(ctx, &ewq);
+
+ down_read(&mm->mmap_sem);
+}
+
static int userfaultfd_release(struct inode *inode, struct file *file)
{
struct userfaultfd_ctx *ctx = file->private_data;
@@ -522,25 +773,36 @@ wakeup:
}
/* fault_pending_wqh.lock must be hold by the caller */
-static inline struct userfaultfd_wait_queue *find_userfault(
- struct userfaultfd_ctx *ctx)
+static inline struct userfaultfd_wait_queue *find_userfault_in(
+ wait_queue_head_t *wqh)
{
wait_queue_t *wq;
struct userfaultfd_wait_queue *uwq;
- VM_BUG_ON(!spin_is_locked(&ctx->fault_pending_wqh.lock));
+ VM_BUG_ON(!spin_is_locked(&wqh->lock));
uwq = NULL;
- if (!waitqueue_active(&ctx->fault_pending_wqh))
+ if (!waitqueue_active(wqh))
goto out;
/* walk in reverse to provide FIFO behavior to read userfaults */
- wq = list_last_entry(&ctx->fault_pending_wqh.task_list,
- typeof(*wq), task_list);
+ wq = list_last_entry(&wqh->task_list, typeof(*wq), task_list);
uwq = container_of(wq, struct userfaultfd_wait_queue, wq);
out:
return uwq;
}
+static inline struct userfaultfd_wait_queue *find_userfault(
+ struct userfaultfd_ctx *ctx)
+{
+ return find_userfault_in(&ctx->fault_pending_wqh);
+}
+
+static inline struct userfaultfd_wait_queue *find_userfault_evt(
+ struct userfaultfd_ctx *ctx)
+{
+ return find_userfault_in(&ctx->event_wqh);
+}
+
static unsigned int userfaultfd_poll(struct file *file, poll_table *wait)
{
struct userfaultfd_ctx *ctx = file->private_data;
@@ -572,10 +834,42 @@ static unsigned int userfaultfd_poll(struct file *file, poll_table *wait)
smp_mb();
if (waitqueue_active(&ctx->fault_pending_wqh))
ret = POLLIN;
+ else if (waitqueue_active(&ctx->event_wqh))
+ ret = POLLIN;
+
return ret;
default:
- BUG();
+ WARN_ON_ONCE(1);
+ return POLLERR;
+ }
+}
+
+static const struct file_operations userfaultfd_fops;
+
+static int resolve_userfault_fork(struct userfaultfd_ctx *ctx,
+ struct userfaultfd_ctx *new,
+ struct uffd_msg *msg)
+{
+ int fd;
+ struct file *file;
+ unsigned int flags = new->flags & UFFD_SHARED_FCNTL_FLAGS;
+
+ fd = get_unused_fd_flags(flags);
+ if (fd < 0)
+ return fd;
+
+ file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, new,
+ O_RDWR | flags);
+ if (IS_ERR(file)) {
+ put_unused_fd(fd);
+ return PTR_ERR(file);
}
+
+ fd_install(fd, file);
+ msg->arg.reserved.reserved1 = 0;
+ msg->arg.fork.ufd = fd;
+
+ return 0;
}
static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
@@ -584,6 +878,15 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
ssize_t ret;
DECLARE_WAITQUEUE(wait, current);
struct userfaultfd_wait_queue *uwq;
+ /*
+ * Handling fork event requires sleeping operations, so
+ * we drop the event_wqh lock, then do these ops, then
+ * lock it back and wake up the waiter. While the lock is
+ * dropped the ewq may go away so we keep track of it
+ * carefully.
+ */
+ LIST_HEAD(fork_event);
+ struct userfaultfd_ctx *fork_nctx = NULL;
/* always take the fd_wqh lock before the fault_pending_wqh lock */
spin_lock(&ctx->fd_wqh.lock);
@@ -635,6 +938,29 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
break;
}
spin_unlock(&ctx->fault_pending_wqh.lock);
+
+ spin_lock(&ctx->event_wqh.lock);
+ uwq = find_userfault_evt(ctx);
+ if (uwq) {
+ *msg = uwq->msg;
+
+ if (uwq->msg.event == UFFD_EVENT_FORK) {
+ fork_nctx = (struct userfaultfd_ctx *)
+ (unsigned long)
+ uwq->msg.arg.reserved.reserved1;
+ list_move(&uwq->wq.task_list, &fork_event);
+ spin_unlock(&ctx->event_wqh.lock);
+ ret = 0;
+ break;
+ }
+
+ userfaultfd_event_complete(ctx, uwq);
+ spin_unlock(&ctx->event_wqh.lock);
+ ret = 0;
+ break;
+ }
+ spin_unlock(&ctx->event_wqh.lock);
+
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
@@ -651,6 +977,23 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
__set_current_state(TASK_RUNNING);
spin_unlock(&ctx->fd_wqh.lock);
+ if (!ret && msg->event == UFFD_EVENT_FORK) {
+ ret = resolve_userfault_fork(ctx, fork_nctx, msg);
+
+ if (!ret) {
+ spin_lock(&ctx->event_wqh.lock);
+ if (!list_empty(&fork_event)) {
+ uwq = list_first_entry(&fork_event,
+ typeof(*uwq),
+ wq.task_list);
+ list_del(&uwq->wq.task_list);
+ __add_wait_queue(&ctx->event_wqh, &uwq->wq);
+ userfaultfd_event_complete(ctx, uwq);
+ }
+ spin_unlock(&ctx->event_wqh.lock);
+ }
+ }
+
return ret;
}
@@ -753,6 +1096,12 @@ static __always_inline int validate_range(struct mm_struct *mm,
return 0;
}
+static inline bool vma_can_userfault(struct vm_area_struct *vma)
+{
+ return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
+ vma_is_shmem(vma);
+}
+
static int userfaultfd_register(struct userfaultfd_ctx *ctx,
unsigned long arg)
{
@@ -763,6 +1112,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
struct uffdio_register __user *user_uffdio_register;
unsigned long vm_flags, new_flags;
bool found;
+ bool non_anon_pages;
unsigned long start, end, vma_end;
user_uffdio_register = (struct uffdio_register __user *) arg;
@@ -814,13 +1164,21 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
goto out_unlock;
/*
+ * If the first vma contains huge pages, make sure start address
+ * is aligned to huge page size.
+ */
+ if (is_vm_hugetlb_page(vma)) {
+ unsigned long vma_hpagesize = vma_kernel_pagesize(vma);
+
+ if (start & (vma_hpagesize - 1))
+ goto out_unlock;
+ }
+
+ /*
* Search for not compatible vmas.
- *
- * FIXME: this shall be relaxed later so that it doesn't fail
- * on tmpfs backed vmas (in addition to the current allowance
- * on anonymous vmas).
*/
found = false;
+ non_anon_pages = false;
for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
cond_resched();
@@ -829,8 +1187,21 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
/* check not compatible vmas */
ret = -EINVAL;
- if (cur->vm_ops)
+ if (!vma_can_userfault(cur))
goto out_unlock;
+ /*
+ * If this vma contains ending address, and huge pages
+ * check alignment.
+ */
+ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end &&
+ end > cur->vm_start) {
+ unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
+
+ ret = -EINVAL;
+
+ if (end & (vma_hpagesize - 1))
+ goto out_unlock;
+ }
/*
* Check that this vma isn't already owned by a
@@ -843,6 +1214,12 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
cur->vm_userfaultfd_ctx.ctx != ctx)
goto out_unlock;
+ /*
+ * Note vmas containing huge pages
+ */
+ if (is_vm_hugetlb_page(cur) || vma_is_shmem(cur))
+ non_anon_pages = true;
+
found = true;
}
BUG_ON(!found);
@@ -854,7 +1231,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
do {
cond_resched();
- BUG_ON(vma->vm_ops);
+ BUG_ON(!vma_can_userfault(vma));
BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
vma->vm_userfaultfd_ctx.ctx != ctx);
@@ -912,7 +1289,8 @@ out_unlock:
* userland which ioctls methods are guaranteed to
* succeed on this range.
*/
- if (put_user(UFFD_API_RANGE_IOCTLS,
+ if (put_user(non_anon_pages ? UFFD_API_RANGE_IOCTLS_BASIC :
+ UFFD_API_RANGE_IOCTLS,
&user_uffdio_register->ioctls))
ret = -EFAULT;
}
@@ -959,11 +1337,18 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
goto out_unlock;
/*
+ * If the first vma contains huge pages, make sure start address
+ * is aligned to huge page size.
+ */
+ if (is_vm_hugetlb_page(vma)) {
+ unsigned long vma_hpagesize = vma_kernel_pagesize(vma);
+
+ if (start & (vma_hpagesize - 1))
+ goto out_unlock;
+ }
+
+ /*
* Search for not compatible vmas.
- *
- * FIXME: this shall be relaxed later so that it doesn't fail
- * on tmpfs backed vmas (in addition to the current allowance
- * on anonymous vmas).
*/
found = false;
ret = -EINVAL;
@@ -980,7 +1365,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
* provides for more strict behavior to notice
* unregistration errors.
*/
- if (cur->vm_ops)
+ if (!vma_can_userfault(cur))
goto out_unlock;
found = true;
@@ -994,7 +1379,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
do {
cond_resched();
- BUG_ON(vma->vm_ops);
+ BUG_ON(!vma_can_userfault(vma));
/*
* Nothing to do: this vma is already registered into this
@@ -1007,6 +1392,19 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
start = vma->vm_start;
vma_end = min(end, vma->vm_end);
+ if (userfaultfd_missing(vma)) {
+ /*
+ * Wake any concurrent pending userfault while
+ * we unregister, so they will not hang
+ * permanently and it avoids userland to call
+ * UFFDIO_WAKE explicitly.
+ */
+ struct userfaultfd_wake_range range;
+ range.start = start;
+ range.len = vma_end - start;
+ wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range);
+ }
+
new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP);
prev = vma_merge(mm, prev, start, vma_end, new_flags,
vma->anon_vma, vma->vm_file, vma->vm_pgoff,
@@ -1178,6 +1576,14 @@ out:
return ret;
}
+static inline unsigned int uffd_ctx_features(__u64 user_features)
+{
+ /*
+ * For the current set of features the bits just coincide
+ */
+ return (unsigned int)user_features;
+}
+
/*
* userland asks for a certain API version and we return which bits
* and ioctl commands are implemented in this kernel for such API
@@ -1189,6 +1595,7 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
struct uffdio_api uffdio_api;
void __user *buf = (void __user *)arg;
int ret;
+ __u64 features;
ret = -EINVAL;
if (ctx->state != UFFD_STATE_WAIT_API)
@@ -1196,19 +1603,23 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
ret = -EFAULT;
if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api)))
goto out;
- if (uffdio_api.api != UFFD_API || uffdio_api.features) {
+ features = uffdio_api.features;
+ if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) {
memset(&uffdio_api, 0, sizeof(uffdio_api));
if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
goto out;
ret = -EINVAL;
goto out;
}
+ /* report all available features and ioctls to userland */
uffdio_api.features = UFFD_API_FEATURES;
uffdio_api.ioctls = UFFD_API_IOCTLS;
ret = -EFAULT;
if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
goto out;
ctx->state = UFFD_STATE_RUNNING;
+ /* only enable the requested features for this uffd context */
+ ctx->features = uffd_ctx_features(features);
ret = 0;
out:
return ret;
@@ -1295,6 +1706,7 @@ static void init_once_userfaultfd_ctx(void *mem)
init_waitqueue_head(&ctx->fault_pending_wqh);
init_waitqueue_head(&ctx->fault_wqh);
+ init_waitqueue_head(&ctx->event_wqh);
init_waitqueue_head(&ctx->fd_wqh);
seqcount_init(&ctx->refile_seq);
}
@@ -1335,6 +1747,7 @@ static struct file *userfaultfd_file_create(int flags)
atomic_set(&ctx->refcount, 1);
ctx->flags = flags;
+ ctx->features = 0;
ctx->state = UFFD_STATE_WAIT_API;
ctx->released = false;
ctx->mm = current->mm;