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find_or_create_page(9) [centos man page]

FIND_OR_CREATE_PAGE(9)					    Memory Management in Linux					    FIND_OR_CREATE_PAGE(9)

find_or_create_page - locate or add a pagecache page SYNOPSIS
struct page * find_or_create_page(struct address_space * mapping, pgoff_t index, gfp_t gfp_mask); ARGUMENTS
mapping the page's address_space index the page's index into the mapping gfp_mask page allocation mode DESCRIPTION
Looks up the page cache slot at mapping & offset. If there is a page cache page, it is returned locked and with an increased refcount. If the page is not present, a new page is allocated using gfp_mask and added to the page cache and the VM's LRU list. The page is returned locked and with an increased refcount. On memory exhaustion, NULL is returned. find_or_create_page may sleep, even if gfp_flags specifies an atomic allocation! COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 FIND_OR_CREATE_PAGE(9)

Check Out this Related Man Page

VM_PAGE_ALLOC(9)					   BSD Kernel Developer's Manual					  VM_PAGE_ALLOC(9)

vm_page_alloc -- allocate a page for a vm_object SYNOPSIS
#include <sys/param.h> #include <vm/vm.h> #include <vm/vm_page.h> vm_page_t vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req); DESCRIPTION
The vm_page_alloc() function allocates a page at pindex within object. It is assumed that a page has not already been allocated at pindex. The page returned is inserted into the object, unless VM_ALLOC_NOOBJ is specified in the req. The page may exist in the vm object cache, in which case it will be reactivated instead, moving from the cache into the object page list. vm_page_alloc() will not sleep. Its arguments are: object The VM object to allocate the page for. The object must be locked if VM_ALLOC_NOOBJ is not specified. pindex The index into the object at which the page should be inserted. req The bitwise-inclusive OR of a class and any optional flags indicating how the page should be allocated. Exactly one of the following classes must be specified: VM_ALLOC_NORMAL The page should be allocated with no special treatment. VM_ALLOC_SYSTEM The page can be allocated if the cache is empty and the free page count is above the interrupt reserved water mark. This flag should be used only when the system really needs the page. VM_ALLOC_INTERRUPT vm_page_alloc() is being called during an interrupt. A page will be returned successfully if the free page count is greater than zero. The optional flags are: VM_ALLOC_ZERO Indicate a preference for a pre-zeroed page. There is no guarantee that the returned page will be zeroed, but it will have the PG_ZERO flag set if it is zeroed. VM_ALLOC_NOOBJ Do not associate the allocated page with a vm object. The object argument is ignored. VM_ALLOC_NOBUSY The returned page will not have the VPO_BUSY flag set. VM_ALLOC_WIRED The returned page will be wired. VM_ALLOC_IFCACHED Allocate the page only if it is cached. Otherwise, return NULL. VM_ALLOC_IFNOTCACHED Only allocate the page if it is not cached in the object. If the page at the specified pindex is cached, NULL is returned instead. RETURN VALUES
The vm_page_t that was allocated is returned if successful; otherwise, NULL is returned. NOTES
The pager process is always upgraded to VM_ALLOC_SYSTEM unless VM_ALLOC_INTERRUPT is set. AUTHORS
This manual page was written by Chad David <>. BSD
July 3, 2010 BSD
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