Hi, > memmap_init_zone_device() currently mixes refcount policy and core > ZONE_DEVICE page setup in a single helper. > > Factor the refcount-reset predicate into pagemap_requires_refcount_reset(), > move the common page initialization into __zone_device_page_init(), and > wrap the existing slow path in zone_device_page_init_slow(). > > This keeps the slow-path behaviour unchanged and gives later patches > reusable helper boundaries. > > No functional change intended. > > Signed-off-by: Li Zhe <[email protected]> > Reviewed-by: Mike Rapoport (Microsoft) <[email protected]> > > diff --git a/mm/mm_init.c b/mm/mm_init.c > index 95808ab5cfdb..a70acb7431a6 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -1005,11 +1005,37 @@ static void __init memmap_init(void) > } > > #ifdef CONFIG_ZONE_DEVICE > -static void __ref __init_zone_device_page(struct page *page, unsigned long > pfn, > +/* > + * Return true when memmap_init_zone_device() must initialize the page > + * refcount to 0. MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in > + * the free path, while the remaining ZONE_DEVICE types start from 0 here > + * and raise the count again when the allocator or driver hands the page > + * out. > + */ > +static inline bool pagemap_requires_refcount_reset(const struct dev_pagemap > *pgmap) > +{ > + /* > + * MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in the free > + * path. The remaining ZONE_DEVICE types start from 0 here and raise > + * the count again when the allocator or driver hands the page out. > + */ > + switch (pgmap->type) { > + case MEMORY_DEVICE_FS_DAX: > + case MEMORY_DEVICE_PRIVATE: > + case MEMORY_DEVICE_COHERENT: > + case MEMORY_DEVICE_PCI_P2PDMA: > + return true; > + case MEMORY_DEVICE_GENERIC: > + return false; > + } > + > + return false; > +} > + > +static void __ref __zone_device_page_init(struct page *page, unsigned long > pfn, > unsigned long zone_idx, int nid, > struct dev_pagemap *pgmap) > { > - > __init_single_page(page, pfn, zone_idx, nid); > > /* > @@ -1028,23 +1054,15 @@ static void __ref __init_zone_device_page(struct page > *page, unsigned long pfn, > */ > page_folio(page)->pgmap = pgmap; > page->zone_device_data = NULL; > +} > > - /* > - * MEMORY_DEVICE_GENERIC pages regain a refcount of 1 in the free > - * path. The remaining ZONE_DEVICE types start from 0 here and raise > - * the count again when the allocator or driver hands the page out. > - */ > - switch (pgmap->type) { > - case MEMORY_DEVICE_FS_DAX: > - case MEMORY_DEVICE_PRIVATE: > - case MEMORY_DEVICE_COHERENT: > - case MEMORY_DEVICE_PCI_P2PDMA: > +static void __ref zone_device_page_init_slow(struct page *page, > + unsigned long pfn, unsigned long zone_idx, int nid, > + struct dev_pagemap *pgmap) > +{ > + __zone_device_page_init(page, pfn, zone_idx, nid, pgmap); > + if (pagemap_requires_refcount_reset(pgmap)) > set_page_count(page, 0); > - break; > - > - case MEMORY_DEVICE_GENERIC: > - break; > - } > } > > /* > @@ -1090,7 +1108,7 @@ static void __ref memmap_init_compound(struct page > *head, > for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) { > struct page *page = pfn_to_page(pfn); > > - __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); > + zone_device_page_init_slow(page, pfn, zone_idx, nid, pgmap); > prep_compound_tail(page, head, order); > set_page_count(page, 0); > } > @@ -1126,7 +1144,7 @@ void __ref memmap_init_zone_device(struct zone *zone, > for (pfn = start_pfn; pfn < end_pfn; pfn += pfns_per_compound) { > struct page *page = pfn_to_page(pfn); > > - __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); > + zone_device_page_init_slow(page, pfn, zone_idx, nid, pgmap);
It looks like all callers of __init_zone_device_page() are now calling zone_device_page_init_slow() that with series evolution became a thin wrapper for __zone_device_page_init(). Maybe we can just rename __init_zone_device_page() to __zone_device_page_init() and replace the open coded setting of the page count with the call to pagemap_requires_refcount_reset() an be done here? -- Sincerely yours, Mike.
