GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-22 14:41:27 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

userfaultfd: non-cooperative: add event for memory unmaps

Browse source 
When a non-cooperative userfaultfd monitor copies pages in the
background, it may encounter regions that were already unmapped.
Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely
changes in the virtual memory layout.

Since there might be different uffd contexts for the affected VMAs, we
first should create a temporary representation for the unmap event for
each uffd context and then notify them one by one to the appropriate
userfault file descriptors.

The event notification occurs after the mmap_sem has been released.

[arnd@arndb.de: fix nommu build]
  Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de
[mhocko@suse.com: fix nommu build]
  Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Rapoport 2017-02-24 14:58:22 -08:00 • committed by Linus Torvalds
parent 846b1a0f1d
commit 897ab3e0c4
15 changed files with 160 additions and 45 deletions
Download patch file Download diff file Expand all files Collapse all files

65
fs/userfaultfd.c
View file

@ -71,6 +71,13 @@ struct userfaultfd_fork_ctx {
struct list_head list;
};
struct userfaultfd_unmap_ctx {
struct userfaultfd_ctx *ctx;
unsigned long start;
unsigned long end;
struct list_head list;
};
struct userfaultfd_wait_queue {
struct uffd_msg msg;
wait_queue_t wq;
@ -709,6 +716,64 @@ void userfaultfd_remove(struct vm_area_struct *vma,
down_read(&mm->mmap_sem);
}
static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps,
unsigned long start, unsigned long end)
{
struct userfaultfd_unmap_ctx *unmap_ctx;
list_for_each_entry(unmap_ctx, unmaps, list)
if (unmap_ctx->ctx == ctx && unmap_ctx->start == start &&
unmap_ctx->end == end)
return true;
return false;
}
int userfaultfd_unmap_prep(struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct list_head *unmaps)
{
for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
struct userfaultfd_unmap_ctx *unmap_ctx;
struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx;
if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_UNMAP) ||
has_unmap_ctx(ctx, unmaps, start, end))
continue;
unmap_ctx = kzalloc(sizeof(*unmap_ctx), GFP_KERNEL);
if (!unmap_ctx)
return -ENOMEM;
userfaultfd_ctx_get(ctx);
unmap_ctx->ctx = ctx;
unmap_ctx->start = start;
unmap_ctx->end = end;
list_add_tail(&unmap_ctx->list, unmaps);
}
return 0;
}
void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf)
{
struct userfaultfd_unmap_ctx *ctx, *n;
struct userfaultfd_wait_queue ewq;
list_for_each_entry_safe(ctx, n, uf, list) {
msg_init(&ewq.msg);
ewq.msg.event = UFFD_EVENT_UNMAP;
ewq.msg.arg.remove.start = ctx->start;
ewq.msg.arg.remove.end = ctx->end;
userfaultfd_event_wait_completion(ctx->ctx, &ewq);
list_del(&ctx->list);
kfree(ctx);
}
}
static int userfaultfd_release(struct inode *inode, struct file *file)
{
struct userfaultfd_ctx *ctx = file->private_data;