Change folio_lock_or_retry to accept vm_fault struct and return the
vm_fault_t directly.
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
---
include/linux/pagemap.h | 9 ++++-----
mm/filemap.c | 22 ++++++++++++----------
mm/memory.c | 14 ++++++--------
3 files changed, 22 insertions(+), 23 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 716953ee1ebd..0026a0a8277c 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -900,8 +900,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,
void __folio_lock(struct folio *folio);
int __folio_lock_killable(struct folio *folio);
-bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
- unsigned int flags);
+vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf);
void unlock_page(struct page *page);
void folio_unlock(struct folio *folio);
@@ -1005,11 +1004,11 @@ static inline int folio_lock_killable(struct folio *folio)
* Return value and mmap_lock implications depend on flags; see
* __folio_lock_or_retry().
*/
-static inline bool folio_lock_or_retry(struct folio *folio,
- struct mm_struct *mm, unsigned int flags)
+static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
+ struct vm_fault *vmf)
{
might_sleep();
- return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
+ return folio_trylock(folio) ? 0 : __folio_lock_or_retry(folio, vmf);
}
/*
diff --git a/mm/filemap.c b/mm/filemap.c
index 9e44a49bbd74..d245bb4f7153 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1669,32 +1669,34 @@ static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait)
/*
* Return values:
- * true - folio is locked; mmap_lock is still held.
- * false - folio is not locked.
+ * 0 - folio is locked.
+ * VM_FAULT_RETRY - folio is not locked.
* mmap_lock has been released (mmap_read_unlock(), unless flags had both
* FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
* which case mmap_lock is still held.
*
- * If neither ALLOW_RETRY nor KILLABLE are set, will always return true
+ * If neither ALLOW_RETRY nor KILLABLE are set, will always return 0
* with the folio locked and the mmap_lock unperturbed.
*/
-bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
- unsigned int flags)
+vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf)
{
+ struct mm_struct *mm = vmf->vma->vm_mm;
+ unsigned int flags = vmf->flags;
+
if (fault_flag_allow_retry_first(flags)) {
/*
* CAUTION! In this case, mmap_lock is not released
- * even though return 0.
+ * even though return VM_FAULT_RETRY.
*/
if (flags & FAULT_FLAG_RETRY_NOWAIT)
- return false;
+ return VM_FAULT_RETRY;
mmap_read_unlock(mm);
if (flags & FAULT_FLAG_KILLABLE)
folio_wait_locked_killable(folio);
else
folio_wait_locked(folio);
- return false;
+ return VM_FAULT_RETRY;
}
if (flags & FAULT_FLAG_KILLABLE) {
bool ret;
@@ -1702,13 +1704,13 @@ bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
ret = __folio_lock_killable(folio);
if (ret) {
mmap_read_unlock(mm);
- return false;
+ return VM_FAULT_RETRY;
}
} else {
__folio_lock(folio);
}
- return true;
+ return 0;
}
/**
diff --git a/mm/memory.c b/mm/memory.c
index 5f26c56ce979..4ae3f046f593 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3582,6 +3582,7 @@ static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
struct folio *folio = page_folio(vmf->page);
struct vm_area_struct *vma = vmf->vma;
struct mmu_notifier_range range;
+ vm_fault_t ret;
/*
* We need a reference to lock the folio because we don't hold
@@ -3594,9 +3595,10 @@ static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
if (!folio_try_get(folio))
return 0;
- if (!folio_lock_or_retry(folio, vma->vm_mm, vmf->flags)) {
+ ret = folio_lock_or_retry(folio, vmf);
+ if (ret) {
folio_put(folio);
- return VM_FAULT_RETRY;
+ return ret;
}
mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0,
vma->vm_mm, vmf->address & PAGE_MASK,
@@ -3721,7 +3723,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
bool exclusive = false;
swp_entry_t entry;
pte_t pte;
- int locked;
vm_fault_t ret = 0;
void *shadow = NULL;
@@ -3844,12 +3845,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
goto out_release;
}
- locked = folio_lock_or_retry(folio, vma->vm_mm, vmf->flags);
-
- if (!locked) {
- ret |= VM_FAULT_RETRY;
+ ret |= folio_lock_or_retry(folio, vmf);
+ if (ret & VM_FAULT_RETRY)
goto out_release;
- }
if (swapcache) {
/*
--
2.41.0.255.g8b1d071c50-googOn Thu, Jun 29, 2023 at 07:04:33PM -0700, Suren Baghdasaryan wrote:
> Change folio_lock_or_retry to accept vm_fault struct and return the
> vm_fault_t directly.
I thought we decided to call this folio_lock_fault()?
> +static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
> + struct vm_fault *vmf)
> {
> might_sleep();
> - return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
> + return folio_trylock(folio) ? 0 : __folio_lock_or_retry(folio, vmf);
No, don't use the awful ternary operator. The || form is used
everywhere else.
> /*
> * Return values:
> - * true - folio is locked; mmap_lock is still held.
> - * false - folio is not locked.
> + * 0 - folio is locked.
> + * VM_FAULT_RETRY - folio is not locked.
I don't think we want to be so prescriptive here. It returns non-zero
if the folio is not locked. The precise value is not something that
callers should depend on.
On Thu, Jun 29, 2023 at 8:36 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Jun 29, 2023 at 07:04:33PM -0700, Suren Baghdasaryan wrote:
> > Change folio_lock_or_retry to accept vm_fault struct and return the
> > vm_fault_t directly.
>
> I thought we decided to call this folio_lock_fault()?
>
> > +static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
> > + struct vm_fault *vmf)
> > {
> > might_sleep();
> > - return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
> > + return folio_trylock(folio) ? 0 : __folio_lock_or_retry(folio, vmf);
>
> No, don't use the awful ternary operator. The || form is used
> everywhere else.
Ok, but folio_trylock() returns a boolean while folio_lock_or_retry
should return vm_fault_t. How exactly do you suggest changing this?
Something like this perhaps:
static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
struct vm_fault *vmf)
{
might_sleep();
if (folio_trylock(folio))
return 0;
return __folio_lock_or_retry(folio, mm, flags);
}
?
>
> > /*
> > * Return values:
> > - * true - folio is locked; mmap_lock is still held.
> > - * false - folio is not locked.
> > + * 0 - folio is locked.
> > + * VM_FAULT_RETRY - folio is not locked.
>
> I don't think we want to be so prescriptive here. It returns non-zero
> if the folio is not locked. The precise value is not something that
> callers should depend on.
Ok, I'll change it to "non-zero" here.
>
On Thu, Jun 29, 2023 at 08:45:39PM -0700, Suren Baghdasaryan wrote:
> On Thu, Jun 29, 2023 at 8:36 PM Matthew Wilcox <willy@infradead.org> wrote:
> >
> > On Thu, Jun 29, 2023 at 07:04:33PM -0700, Suren Baghdasaryan wrote:
> > > Change folio_lock_or_retry to accept vm_fault struct and return the
> > > vm_fault_t directly.
> >
> > I thought we decided to call this folio_lock_fault()?
> >
> > > +static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
> > > + struct vm_fault *vmf)
> > > {
> > > might_sleep();
> > > - return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
> > > + return folio_trylock(folio) ? 0 : __folio_lock_or_retry(folio, vmf);
> >
> > No, don't use the awful ternary operator. The || form is used
> > everywhere else.
>
> Ok, but folio_trylock() returns a boolean while folio_lock_or_retry
> should return vm_fault_t. How exactly do you suggest changing this?
> Something like this perhaps:
>
> static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
> struct vm_fault *vmf)
> {
> might_sleep();
> if (folio_trylock(folio))
> return 0;
> return __folio_lock_or_retry(folio, mm, flags);
> }
>
> ?
I think the automatic casting would work, but I prefer what you've
written here.
> > > /*
> > > * Return values:
> > > - * true - folio is locked; mmap_lock is still held.
> > > - * false - folio is not locked.
> > > + * 0 - folio is locked.
> > > + * VM_FAULT_RETRY - folio is not locked.
> >
> > I don't think we want to be so prescriptive here. It returns non-zero
> > if the folio is not locked. The precise value is not something that
> > callers should depend on.
>
> Ok, I'll change it to "non-zero" here.
Thanks!
On Thu, Jun 29, 2023 at 8:47 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Jun 29, 2023 at 08:45:39PM -0700, Suren Baghdasaryan wrote:
> > On Thu, Jun 29, 2023 at 8:36 PM Matthew Wilcox <willy@infradead.org> wrote:
> > >
> > > On Thu, Jun 29, 2023 at 07:04:33PM -0700, Suren Baghdasaryan wrote:
> > > > Change folio_lock_or_retry to accept vm_fault struct and return the
> > > > vm_fault_t directly.
> > >
> > > I thought we decided to call this folio_lock_fault()?
> > >
> > > > +static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
> > > > + struct vm_fault *vmf)
> > > > {
> > > > might_sleep();
> > > > - return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
> > > > + return folio_trylock(folio) ? 0 : __folio_lock_or_retry(folio, vmf);
> > >
> > > No, don't use the awful ternary operator. The || form is used
> > > everywhere else.
> >
> > Ok, but folio_trylock() returns a boolean while folio_lock_or_retry
> > should return vm_fault_t. How exactly do you suggest changing this?
> > Something like this perhaps:
> >
> > static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
> > struct vm_fault *vmf)
> > {
> > might_sleep();
> > if (folio_trylock(folio))
> > return 0;
> > return __folio_lock_or_retry(folio, mm, flags);
> > }
> >
> > ?
>
> I think the automatic casting would work, but I prefer what you've
> written here.
>
> > > > /*
> > > > * Return values:
> > > > - * true - folio is locked; mmap_lock is still held.
> > > > - * false - folio is not locked.
> > > > + * 0 - folio is locked.
> > > > + * VM_FAULT_RETRY - folio is not locked.
> > >
> > > I don't think we want to be so prescriptive here. It returns non-zero
> > > if the folio is not locked. The precise value is not something that
> > > callers should depend on.
> >
> > Ok, I'll change it to "non-zero" here.
>
> Thanks!
Posted v7 at https://lore.kernel.org/all/20230630211957.1341547-1-surenb@google.com/
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