search for: devmap_managed_enable_get

...+EXPORT_SYMBOL(devmap_managed_key); > +static atomic_t devmap_managed_enable; > + > +static void devmap_managed_enable_put(void *data) > +{ > + if (atomic_dec_and_test(&devmap_managed_enable)) > + static_branch_disable(&devmap_managed_key); > +} > + > +static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap) > +{ > + if (!pgmap->ops->page_free) { NIT: later on you add the check for pgmap->ops... it should probably be here. But not sure that bisection will be an issue here. Reviewed-by: Ira Weiny <ira.weiny at intel.com> > + WA...

...DEFINE_STATIC_KEY_FALSE(devmap_managed_key); +EXPORT_SYMBOL(devmap_managed_key); +static atomic_t devmap_managed_enable; + +static void devmap_managed_enable_put(void *data) +{ + if (atomic_dec_and_test(&devmap_managed_enable)) + static_branch_disable(&devmap_managed_key); +} + +static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap) +{ + if (!pgmap->ops->page_free) { + WARN(1, "Missing page_free method\n"); + return -EINVAL; + } + + if (atomic_inc_return(&devmap_managed_enable) == 1) + static_branch_enable(&devmap_managed_key); + return devm_add_action_o...

...p_compat_align(void) EXPORT_SYMBOL_GPL(memremap_compat_align); #endif -#ifdef CONFIG_DEV_PAGEMAP_OPS -DEFINE_STATIC_KEY_FALSE(devmap_managed_key); -EXPORT_SYMBOL(devmap_managed_key); - -static void devmap_managed_enable_put(void) -{ - static_branch_dec(&devmap_managed_key); -} - -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) -{ - if (pgmap->type == MEMORY_DEVICE_PRIVATE && - (!pgmap->ops || !pgmap->ops->page_free)) { - WARN(1, "Missing page_free method\n"); - return -EINVAL; - } - - static_branch_inc(&devmap_managed_key); - return 0; -} -#else -static i...

...; > #endif > > -#ifdef CONFIG_DEV_PAGEMAP_OPS > -DEFINE_STATIC_KEY_FALSE(devmap_managed_key); > -EXPORT_SYMBOL(devmap_managed_key); > - > -static void devmap_managed_enable_put(void) > -{ > - static_branch_dec(&devmap_managed_key); > -} > - > -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) > -{ > - if (pgmap->type == MEMORY_DEVICE_PRIVATE && > - (!pgmap->ops || !pgmap->ops->page_free)) { > - WARN(1, "Missing page_free method\n"); > - return -EINVAL; > - } > - > - static_branch_inc(&devmap_manag...

ZONE_DEVICE struct pages have an extra reference count that complicates the code for put_page() and several places in the kernel that need to check the reference count to see that a page is not being used (gup, compaction, migration, etc.). Clean up the code so the reference count doesn't need to be treated specially for ZONE_DEVICE. Signed-off-by: Ralph Campbell <rcampbell at

..._OPS -DEFINE_STATIC_KEY_FALSE(devmap_managed_key); -EXPORT_SYMBOL(devmap_managed_key); -static atomic_t devmap_managed_enable; - -static void devmap_managed_enable_put(void) -{ - if (atomic_dec_and_test(&devmap_managed_enable)) - static_branch_disable(&devmap_managed_key); -} - -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) -{ - if (pgmap->type == MEMORY_DEVICE_PRIVATE && - (!pgmap->ops || !pgmap->ops->page_free)) { - WARN(1, "Missing page_free method\n"); - return -EINVAL; - } - - if (atomic_inc_return(&devmap_managed_enable) == 1) - static_branch_en...

...p_compat_align(void) EXPORT_SYMBOL_GPL(memremap_compat_align); #endif -#ifdef CONFIG_DEV_PAGEMAP_OPS -DEFINE_STATIC_KEY_FALSE(devmap_managed_key); -EXPORT_SYMBOL(devmap_managed_key); - -static void devmap_managed_enable_put(void) -{ - static_branch_dec(&devmap_managed_key); -} - -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) -{ - if (pgmap->type == MEMORY_DEVICE_PRIVATE && - (!pgmap->ops || !pgmap->ops->page_free)) { - WARN(1, "Missing page_free method\n"); - return -EINVAL; - } - - static_branch_inc(&devmap_managed_key); - return 0; -} -#else -static i...

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

...++ b/kernel/memremap.c @@ -11,7 +11,6 @@ #include <linux/types.h> #include <linux/wait_bit.h> #include <linux/xarray.h> -#include <linux/hmm.h> static DEFINE_XARRAY(pgmap_array); #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1) @@ -46,36 +45,6 @@ static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgm } #endif /* CONFIG_DEV_PAGEMAP_OPS */ -#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) -vm_fault_t device_private_entry_fault(struct vm_area_struct *vma, - unsigned long addr, - swp_entry_t entry, - unsigned int flags, - pmd_t *p...

...ion done; struct device *dev; enum memory_type type; unsigned int flags; diff --git a/kernel/memremap.c b/kernel/memremap.c index eee490e7d7e1..bea6f887adad 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -29,7 +29,7 @@ static void devmap_managed_enable_put(void *data) static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap) { - if (!pgmap->ops->page_free) { + if (!pgmap->ops || !pgmap->ops->page_free) { WARN(1, "Missing page_free method\n"); return -EINVAL; } @@ -75,6 +75,24 @@ static unsigned long pfn_next(unsigned long pfn) #define for...

...emory_type type; > unsigned int flags; > diff --git a/kernel/memremap.c b/kernel/memremap.c > index eee490e7d7e1..bea6f887adad 100644 > --- a/kernel/memremap.c > +++ b/kernel/memremap.c > @@ -29,7 +29,7 @@ static void devmap_managed_enable_put(void *data) > > static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap) > { > - if (!pgmap->ops->page_free) { > + if (!pgmap->ops || !pgmap->ops->page_free) { > WARN(1, "Missing page_free method\n"); > return -EINVAL; > } > @@ -75,6 +75,24 @@ static unsigned long pfn_n...

Hi Dan, Jérôme and Jason, below is a series that cleans up the dev_pagemap interface so that it is more easily usable, which removes the need to wrap it in hmm and thus allowing to kill a lot of code Note: this series is on top of Linux 5.2-rc5 and has some minor conflicts with the hmm tree that are easy to resolve. Diffstat summary: 32 files changed, 361 insertions(+), 1012 deletions(-) Git

...d_unless(page, 1, 1)) + if (!page_ref_add_unless(page, 1, 0)) return NULL; return page; } diff --git a/mm/memremap.c b/mm/memremap.c index 504a10ff2edf..a163a9e36e56 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -49,12 +49,6 @@ static void devmap_managed_enable_put(void) static int devmap_managed_enable_get(struct dev_pagemap *pgmap) { - if (pgmap->type == MEMORY_DEVICE_PRIVATE && - (!pgmap->ops || !pgmap->ops->page_free)) { - WARN(1, "Missing page_free method\n"); - return -EINVAL; - } - static_branch_inc(&devmap_managed_key); return 0; } @@ -92,13 +86,6...

...inline void free_zone_device_page(struct page *page) +{ +} +#endif + #endif /* __MM_INTERNAL_H */ diff --git a/mm/memremap.c b/mm/memremap.c index 504a10ff2edf..a163a9e36e56 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -49,12 +49,6 @@ static void devmap_managed_enable_put(void) static int devmap_managed_enable_get(struct dev_pagemap *pgmap) { - if (pgmap->type == MEMORY_DEVICE_PRIVATE && - (!pgmap->ops || !pgmap->ops->page_free)) { - WARN(1, "Missing page_free method\n"); - return -EINVAL; - } - static_branch_inc(&devmap_managed_key); return 0; } @@ -92,13 +86,6...