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mm: introduce fault_env

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The idea borrowed from Peter's patch from patchset on speculative page
faults[1]:

Instead of passing around the endless list of function arguments,
replace the lot with a single structure so we can change context without
endless function signature changes.

The changes are mostly mechanical with exception of faultaround code:
filemap_map_pages() got reworked a bit.

This patch is preparation for the next one.

[1] http://lkml.kernel.org/r/20141020222841.302891540@infradead.org

Link: http://lkml.kernel.org/r/1466021202-61880-9-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2016-07-26 15:25:20 -07:00 • committed by Linus Torvalds
parent dcddffd41d
commit bae473a423
10 changed files with 474 additions and 515 deletions
Download patch file Download diff file Expand all files Collapse all files

22
fs/userfaultfd.c
View file

@ -257,10 +257,9 @@ out:
* fatal_signal_pending()s, and the mmap_sem must be released before
* returning it.
*/
int handle_userfault(struct vm_area_struct *vma, unsigned long address,
unsigned int flags, unsigned long reason)
int handle_userfault(struct fault_env *fe, unsigned long reason)
{
struct mm_struct *mm = vma->vm_mm;
struct mm_struct *mm = fe->vma->vm_mm;
struct userfaultfd_ctx *ctx;
struct userfaultfd_wait_queue uwq;
int ret;
@ -269,7 +268,7 @@ int handle_userfault(struct vm_area_struct *vma, unsigned long address,
BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
ret = VM_FAULT_SIGBUS;
ctx = vma->vm_userfaultfd_ctx.ctx;
ctx = fe->vma->vm_userfaultfd_ctx.ctx;
if (!ctx)
goto out;
@ -302,17 +301,17 @@ int handle_userfault(struct vm_area_struct *vma, unsigned long address,
* without first stopping userland access to the memory. For
* VM_UFFD_MISSING userfaults this is enough for now.
*/
if (unlikely(!(flags & FAULT_FLAG_ALLOW_RETRY))) {
if (unlikely(!(fe->flags & FAULT_FLAG_ALLOW_RETRY))) {
/*
* Validate the invariant that nowait must allow retry
* to be sure not to return SIGBUS erroneously on
* nowait invocations.
*/
BUG_ON(flags & FAULT_FLAG_RETRY_NOWAIT);
BUG_ON(fe->flags & FAULT_FLAG_RETRY_NOWAIT);
#ifdef CONFIG_DEBUG_VM
if (printk_ratelimit()) {
printk(KERN_WARNING
"FAULT_FLAG_ALLOW_RETRY missing %x\n", flags);
"FAULT_FLAG_ALLOW_RETRY missing %x\n", fe->flags);
dump_stack();
}
#endif
@ -324,7 +323,7 @@ int handle_userfault(struct vm_area_struct *vma, unsigned long address,
* and wait.
*/
ret = VM_FAULT_RETRY;
if (flags & FAULT_FLAG_RETRY_NOWAIT)
if (fe->flags & FAULT_FLAG_RETRY_NOWAIT)
goto out;
/* take the reference before dropping the mmap_sem */
@ -332,10 +331,11 @@ int handle_userfault(struct vm_area_struct *vma, unsigned long address,
init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function);
uwq.wq.private = current;
uwq.msg = userfault_msg(address, flags, reason);
uwq.msg = userfault_msg(fe->address, fe->flags, reason);
uwq.ctx = ctx;
return_to_userland = (flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) ==
return_to_userland =
(fe->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) ==
(FAULT_FLAG_USER|FAULT_FLAG_KILLABLE);
spin_lock(&ctx->fault_pending_wqh.lock);
@ -353,7 +353,7 @@ int handle_userfault(struct vm_area_struct *vma, unsigned long address,
TASK_KILLABLE);
spin_unlock(&ctx->fault_pending_wqh.lock);
must_wait = userfaultfd_must_wait(ctx, address, flags, reason);
must_wait = userfaultfd_must_wait(ctx, fe->address, fe->flags, reason);
up_read(&mm->mmap_sem);
if (likely(must_wait && !ACCESS_ONCE(ctx->released) &&