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6189eb82f0
There is 8 byte page_ext->flags field allocated per page whenever CONFIG_PAGE_EXTENSION is enabled. However, not every user of page_ext uses flags. Therefore, check whether flags is needed at least by one user and if so allocate space for it. For example when page_table_check is enabled, on a machine with 128G of memory before the fix: [ 2.244288] allocated 536870912 bytes of page_ext after the fix: [ 2.160154] allocated 268435456 bytes of page_ext Also, add a kernel-doc comment before page_ext_operations that describes the fields, and remove check if need() is set, as that is now a required field. [pasha.tatashin@soleen.com: address comments from Mike Rapoport] Link: https://lkml.kernel.org/r/20230117202103.1412449-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20230113154253.92480-1-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Charan Teja Kalla <quic_charante@quicinc.com> Cc: Li Zhe <lizhe.67@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
125 lines
2.8 KiB
C
125 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_PAGE_EXT_H
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#define __LINUX_PAGE_EXT_H
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#include <linux/types.h>
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#include <linux/stacktrace.h>
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#include <linux/stackdepot.h>
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struct pglist_data;
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/**
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* struct page_ext_operations - per page_ext client operations
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* @offset: Offset to the client's data within page_ext. Offset is returned to
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* the client by page_ext_init.
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* @size: The size of the client data within page_ext.
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* @need: Function that returns true if client requires page_ext.
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* @init: (optional) Called to initialize client once page_exts are allocated.
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* @need_shared_flags: True when client is using shared page_ext->flags
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* field.
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*
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* Each Page Extension client must define page_ext_operations in
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* page_ext_ops array.
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*/
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struct page_ext_operations {
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size_t offset;
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size_t size;
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bool (*need)(void);
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void (*init)(void);
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bool need_shared_flags;
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};
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#ifdef CONFIG_PAGE_EXTENSION
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/*
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* The page_ext_flags users must set need_shared_flags to true.
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*/
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enum page_ext_flags {
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PAGE_EXT_OWNER,
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PAGE_EXT_OWNER_ALLOCATED,
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#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
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PAGE_EXT_YOUNG,
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PAGE_EXT_IDLE,
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#endif
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};
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/*
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* Page Extension can be considered as an extended mem_map.
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* A page_ext page is associated with every page descriptor. The
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* page_ext helps us add more information about the page.
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* All page_ext are allocated at boot or memory hotplug event,
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* then the page_ext for pfn always exists.
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*/
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struct page_ext {
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unsigned long flags;
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};
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extern bool early_page_ext;
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extern unsigned long page_ext_size;
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extern void pgdat_page_ext_init(struct pglist_data *pgdat);
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static inline bool early_page_ext_enabled(void)
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{
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return early_page_ext;
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}
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#ifdef CONFIG_SPARSEMEM
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static inline void page_ext_init_flatmem(void)
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{
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}
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extern void page_ext_init(void);
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static inline void page_ext_init_flatmem_late(void)
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{
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}
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#else
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extern void page_ext_init_flatmem(void);
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extern void page_ext_init_flatmem_late(void);
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static inline void page_ext_init(void)
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{
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}
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#endif
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extern struct page_ext *page_ext_get(struct page *page);
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extern void page_ext_put(struct page_ext *page_ext);
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static inline struct page_ext *page_ext_next(struct page_ext *curr)
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{
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void *next = curr;
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next += page_ext_size;
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return next;
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}
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#else /* !CONFIG_PAGE_EXTENSION */
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struct page_ext;
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static inline bool early_page_ext_enabled(void)
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{
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return false;
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}
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static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
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{
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}
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static inline void page_ext_init(void)
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{
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}
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static inline void page_ext_init_flatmem_late(void)
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{
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}
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static inline void page_ext_init_flatmem(void)
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{
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}
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static inline struct page_ext *page_ext_get(struct page *page)
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{
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return NULL;
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}
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static inline void page_ext_put(struct page_ext *page_ext)
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{
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}
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#endif /* CONFIG_PAGE_EXTENSION */
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#endif /* __LINUX_PAGE_EXT_H */
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