linux-stable/mm/internal.h
Ying Han 4779280d1e mm: make get_user_pages() interruptible
The initial implementation of checking TIF_MEMDIE covers the cases of OOM
killing.  If the process has been OOM killed, the TIF_MEMDIE is set and it
return immediately.  This patch includes:

1.  add the case that the SIGKILL is sent by user processes.  The
   process can try to get_user_pages() unlimited memory even if a user
   process has sent a SIGKILL to it(maybe a monitor find the process
   exceed its memory limit and try to kill it).  In the old
   implementation, the SIGKILL won't be handled until the get_user_pages()
   returns.

2.  change the return value to be ERESTARTSYS.  It makes no sense to
   return ENOMEM if the get_user_pages returned by getting a SIGKILL
   signal.  Considering the general convention for a system call
   interrupted by a signal is ERESTARTNOSYS, so the current return value
   is consistant to that.

Lee:

An unfortunate side effect of "make-get_user_pages-interruptible" is that
it prevents a SIGKILL'd task from munlock-ing pages that it had mlocked,
resulting in freeing of mlocked pages.  Freeing of mlocked pages, in
itself, is not so bad.  We just count them now--altho' I had hoped to
remove this stat and add PG_MLOCKED to the free pages flags check.

However, consider pages in shared libraries mapped by more than one task
that a task mlocked--e.g., via mlockall().  If the task that mlocked the
pages exits via SIGKILL, these pages would be left mlocked and
unevictable.

Proposed fix:

Add another GUP flag to ignore sigkill when calling get_user_pages from
munlock()--similar to Kosaki Motohiro's 'IGNORE_VMA_PERMISSIONS flag for
the same purpose.  We are not actually allocating memory in this case,
which "make-get_user_pages-interruptible" intends to avoid.  We're just
munlocking pages that are already resident and mapped, and we're reusing
get_user_pages() to access those pages.

??  Maybe we should combine 'IGNORE_VMA_PERMISSIONS and '_IGNORE_SIGKILL
into a single flag: GUP_FLAGS_MUNLOCK ???

[Lee.Schermerhorn@hp.com: ignore sigkill in get_user_pages during munlock]
Signed-off-by: Paul Menage <menage@google.com>
Signed-off-by: Ying Han <yinghan@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Rohit Seth <rohitseth@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-06 15:59:08 -08:00

285 lines
7.9 KiB
C

/* internal.h: mm/ internal definitions
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef __MM_INTERNAL_H
#define __MM_INTERNAL_H
#include <linux/mm.h>
void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
unsigned long floor, unsigned long ceiling);
extern void prep_compound_page(struct page *page, unsigned long order);
extern void prep_compound_gigantic_page(struct page *page, unsigned long order);
static inline void set_page_count(struct page *page, int v)
{
atomic_set(&page->_count, v);
}
/*
* Turn a non-refcounted page (->_count == 0) into refcounted with
* a count of one.
*/
static inline void set_page_refcounted(struct page *page)
{
VM_BUG_ON(PageTail(page));
VM_BUG_ON(atomic_read(&page->_count));
set_page_count(page, 1);
}
static inline void __put_page(struct page *page)
{
atomic_dec(&page->_count);
}
/*
* in mm/vmscan.c:
*/
extern int isolate_lru_page(struct page *page);
extern void putback_lru_page(struct page *page);
/*
* in mm/page_alloc.c
*/
extern unsigned long highest_memmap_pfn;
extern void __free_pages_bootmem(struct page *page, unsigned int order);
/*
* function for dealing with page's order in buddy system.
* zone->lock is already acquired when we use these.
* So, we don't need atomic page->flags operations here.
*/
static inline unsigned long page_order(struct page *page)
{
VM_BUG_ON(!PageBuddy(page));
return page_private(page);
}
extern long mlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
extern void munlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
{
munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end);
}
#ifdef CONFIG_UNEVICTABLE_LRU
/*
* unevictable_migrate_page() called only from migrate_page_copy() to
* migrate unevictable flag to new page.
* Note that the old page has been isolated from the LRU lists at this
* point so we don't need to worry about LRU statistics.
*/
static inline void unevictable_migrate_page(struct page *new, struct page *old)
{
if (TestClearPageUnevictable(old))
SetPageUnevictable(new);
}
#else
static inline void unevictable_migrate_page(struct page *new, struct page *old)
{
}
#endif
#ifdef CONFIG_UNEVICTABLE_LRU
/*
* Called only in fault path via page_evictable() for a new page
* to determine if it's being mapped into a LOCKED vma.
* If so, mark page as mlocked.
*/
static inline int is_mlocked_vma(struct vm_area_struct *vma, struct page *page)
{
VM_BUG_ON(PageLRU(page));
if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
return 0;
if (!TestSetPageMlocked(page)) {
inc_zone_page_state(page, NR_MLOCK);
count_vm_event(UNEVICTABLE_PGMLOCKED);
}
return 1;
}
/*
* must be called with vma's mmap_sem held for read, and page locked.
*/
extern void mlock_vma_page(struct page *page);
/*
* Clear the page's PageMlocked(). This can be useful in a situation where
* we want to unconditionally remove a page from the pagecache -- e.g.,
* on truncation or freeing.
*
* It is legal to call this function for any page, mlocked or not.
* If called for a page that is still mapped by mlocked vmas, all we do
* is revert to lazy LRU behaviour -- semantics are not broken.
*/
extern void __clear_page_mlock(struct page *page);
static inline void clear_page_mlock(struct page *page)
{
if (unlikely(TestClearPageMlocked(page)))
__clear_page_mlock(page);
}
/*
* mlock_migrate_page - called only from migrate_page_copy() to
* migrate the Mlocked page flag; update statistics.
*/
static inline void mlock_migrate_page(struct page *newpage, struct page *page)
{
if (TestClearPageMlocked(page)) {
unsigned long flags;
local_irq_save(flags);
__dec_zone_page_state(page, NR_MLOCK);
SetPageMlocked(newpage);
__inc_zone_page_state(newpage, NR_MLOCK);
local_irq_restore(flags);
}
}
/*
* free_page_mlock() -- clean up attempts to free and mlocked() page.
* Page should not be on lru, so no need to fix that up.
* free_pages_check() will verify...
*/
static inline void free_page_mlock(struct page *page)
{
if (unlikely(TestClearPageMlocked(page))) {
unsigned long flags;
local_irq_save(flags);
__dec_zone_page_state(page, NR_MLOCK);
__count_vm_event(UNEVICTABLE_MLOCKFREED);
local_irq_restore(flags);
}
}
#else /* CONFIG_UNEVICTABLE_LRU */
static inline int is_mlocked_vma(struct vm_area_struct *v, struct page *p)
{
return 0;
}
static inline void clear_page_mlock(struct page *page) { }
static inline void mlock_vma_page(struct page *page) { }
static inline void mlock_migrate_page(struct page *new, struct page *old) { }
static inline void free_page_mlock(struct page *page) { }
#endif /* CONFIG_UNEVICTABLE_LRU */
/*
* Return the mem_map entry representing the 'offset' subpage within
* the maximally aligned gigantic page 'base'. Handle any discontiguity
* in the mem_map at MAX_ORDER_NR_PAGES boundaries.
*/
static inline struct page *mem_map_offset(struct page *base, int offset)
{
if (unlikely(offset >= MAX_ORDER_NR_PAGES))
return pfn_to_page(page_to_pfn(base) + offset);
return base + offset;
}
/*
* Iterator over all subpages withing the maximally aligned gigantic
* page 'base'. Handle any discontiguity in the mem_map.
*/
static inline struct page *mem_map_next(struct page *iter,
struct page *base, int offset)
{
if (unlikely((offset & (MAX_ORDER_NR_PAGES - 1)) == 0)) {
unsigned long pfn = page_to_pfn(base) + offset;
if (!pfn_valid(pfn))
return NULL;
return pfn_to_page(pfn);
}
return iter + 1;
}
/*
* FLATMEM and DISCONTIGMEM configurations use alloc_bootmem_node,
* so all functions starting at paging_init should be marked __init
* in those cases. SPARSEMEM, however, allows for memory hotplug,
* and alloc_bootmem_node is not used.
*/
#ifdef CONFIG_SPARSEMEM
#define __paginginit __meminit
#else
#define __paginginit __init
#endif
/* Memory initialisation debug and verification */
enum mminit_level {
MMINIT_WARNING,
MMINIT_VERIFY,
MMINIT_TRACE
};
#ifdef CONFIG_DEBUG_MEMORY_INIT
extern int mminit_loglevel;
#define mminit_dprintk(level, prefix, fmt, arg...) \
do { \
if (level < mminit_loglevel) { \
printk(level <= MMINIT_WARNING ? KERN_WARNING : KERN_DEBUG); \
printk(KERN_CONT "mminit::" prefix " " fmt, ##arg); \
} \
} while (0)
extern void mminit_verify_pageflags_layout(void);
extern void mminit_verify_page_links(struct page *page,
enum zone_type zone, unsigned long nid, unsigned long pfn);
extern void mminit_verify_zonelist(void);
#else
static inline void mminit_dprintk(enum mminit_level level,
const char *prefix, const char *fmt, ...)
{
}
static inline void mminit_verify_pageflags_layout(void)
{
}
static inline void mminit_verify_page_links(struct page *page,
enum zone_type zone, unsigned long nid, unsigned long pfn)
{
}
static inline void mminit_verify_zonelist(void)
{
}
#endif /* CONFIG_DEBUG_MEMORY_INIT */
/* mminit_validate_memmodel_limits is independent of CONFIG_DEBUG_MEMORY_INIT */
#if defined(CONFIG_SPARSEMEM)
extern void mminit_validate_memmodel_limits(unsigned long *start_pfn,
unsigned long *end_pfn);
#else
static inline void mminit_validate_memmodel_limits(unsigned long *start_pfn,
unsigned long *end_pfn)
{
}
#endif /* CONFIG_SPARSEMEM */
#define GUP_FLAGS_WRITE 0x1
#define GUP_FLAGS_FORCE 0x2
#define GUP_FLAGS_IGNORE_VMA_PERMISSIONS 0x4
#define GUP_FLAGS_IGNORE_SIGKILL 0x8
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int len, int flags,
struct page **pages, struct vm_area_struct **vmas);
#endif