search for: dax_layout_is_idle_page

.../fs/dax.c +++ b/fs/dax.c @@ -358,7 +358,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, for_each_mapped_pfn(entry, pfn) { struct page *page = pfn_to_page(pfn); - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); WARN_ON_ONCE(page->mapping && page->mapping != mapping); page->mapping = NULL; page->index = 0; @@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *entry) for_each_mapped_pfn(entry, pfn) { struct page *page = pfn_to_page(pfn); - if (page_ref_coun...

On Fri, Sep 25, 2020 at 01:44:41PM -0700, Ralph Campbell wrote: > error = ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, > + dax_layout_is_idle_page(page), > TASK_INTERRUPTIBLE, 0, 0, > ext4_wait_dax_page(ei)); > +++ b/fs/xfs/xfs_file.c > @@ -750,7 +750,7 @@ xfs_break_dax_layouts( > > *retry = true; > return ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, TASK_...

...ciate_entry(void *entry, struct address_space *mapping, > for_each_mapped_pfn(entry, pfn) { > struct page *page = pfn_to_page(pfn); > > - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); > + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); > WARN_ON_ONCE(page->mapping && page->mapping != mapping); > page->mapping = NULL; > page->index = 0; > @@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *entry) > for_each_mapped_pfn(entry,...

.../fs/dax.c +++ b/fs/dax.c @@ -358,7 +358,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, for_each_mapped_pfn(entry, pfn) { struct page *page = pfn_to_page(pfn); - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); WARN_ON_ONCE(page->mapping && page->mapping != mapping); page->mapping = NULL; page->index = 0; @@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *entry) for_each_mapped_pfn(entry, pfn) { struct page *page = pfn_to_page(pfn); - if (page_ref_coun...

Matthew Wilcox, Ira Weiny, and others have complained that ZONE_DEVICE struct page reference counting is ugly because they are "free" when the reference count is one instead of zero. This leads to explicit checks for ZONE_DEVICE pages in places like put_page(), GUP, THP splitting, and page migration which have to adjust the expected reference count when determining if the page is

This is still an RFC because after looking at the pmem/dax code some more, I realized that the ZONE_DEVICE struct pages are being inserted into the process' page tables with vmf_insert_mixed() and a zero refcount on the ZONE_DEVICE struct page. This is sort of OK because insert_pfn() increments the reference count on the pgmap which is what prevents memunmap_pages() from freeing the struct

...page; > } > diff --git a/include/linux/dax.h b/include/linux/dax.h > index 3f78ed78d1d6..8d29f38645aa 100644 > --- a/include/linux/dax.h > +++ b/include/linux/dax.h > @@ -240,7 +240,7 @@ static inline bool dax_mapping(struct address_space *mapping) > > static inline bool dax_layout_is_idle_page(struct page *page) > { > - return page_ref_count(page) <= 1; > + return page_ref_count(page) == 0; > } > > #endif > diff --git a/include/linux/memremap.h b/include/linux/memremap.h > index e5862746751b..f9224f88e4cd 100644 > --- a/include/linux/memremap.h > +++...

...ount(page); lock_page(page); return page; } diff --git a/include/linux/dax.h b/include/linux/dax.h index 3f78ed78d1d6..8d29f38645aa 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -240,7 +240,7 @@ static inline bool dax_mapping(struct address_space *mapping) static inline bool dax_layout_is_idle_page(struct page *page) { - return page_ref_count(page) <= 1; + return page_ref_count(page) == 0; } #endif diff --git a/include/linux/memremap.h b/include/linux/memremap.h index e5862746751b..f9224f88e4cd 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -65,9 +65,10 @@ enu...

...r DMA, or other * get_user_pages() usages. * diff --git a/include/linux/dax.h b/include/linux/dax.h index f906cf4db1cc..e4920ea6abd3 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -245,7 +245,7 @@ static inline bool dax_mapping(struct address_space *mapping) static inline bool dax_layout_is_idle_page(struct page *page) { - return page_ref_count(page) == 1; + return page_ref_count(page) == 0; } #define dax_wait_page(_inode, _page, _wait_cb) \ diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 86c6c368ce9b..2f63747caf56 100644 --- a/include/linux/memremap.h +++ b/inclu...