mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 16:07:39 +00:00
d6dd50e07c
Pull RCU updates from Ingo Molnar: "The main changes in this cycle were: - changes related to No-CBs CPUs and NO_HZ_FULL - RCU-tasks implementation - torture-test updates - miscellaneous fixes - locktorture updates - RCU documentation updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits) workqueue: Use cond_resched_rcu_qs macro workqueue: Add quiescent state between work items locktorture: Cleanup header usage locktorture: Cannot hold read and write lock locktorture: Fix __acquire annotation for spinlock irq locktorture: Support rwlocks rcu: Eliminate deadlock between CPU hotplug and expedited grace periods locktorture: Document boot/module parameters rcutorture: Rename rcutorture_runnable parameter locktorture: Add test scenario for rwsem_lock locktorture: Add test scenario for mutex_lock locktorture: Make torture scripting account for new _runnable name locktorture: Introduce torture context locktorture: Support rwsems locktorture: Add infrastructure for torturing read locks torture: Address race in module cleanup locktorture: Make statistics generic locktorture: Teach about lock debugging locktorture: Support mutexes locktorture: Add documentation ...
873 lines
23 KiB
C
873 lines
23 KiB
C
/*
|
|
* linux/mm/mlock.c
|
|
*
|
|
* (C) Copyright 1995 Linus Torvalds
|
|
* (C) Copyright 2002 Christoph Hellwig
|
|
*/
|
|
|
|
#include <linux/capability.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/swapops.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/pagevec.h>
|
|
#include <linux/mempolicy.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/export.h>
|
|
#include <linux/rmap.h>
|
|
#include <linux/mmzone.h>
|
|
#include <linux/hugetlb.h>
|
|
#include <linux/memcontrol.h>
|
|
#include <linux/mm_inline.h>
|
|
|
|
#include "internal.h"
|
|
|
|
int can_do_mlock(void)
|
|
{
|
|
if (capable(CAP_IPC_LOCK))
|
|
return 1;
|
|
if (rlimit(RLIMIT_MEMLOCK) != 0)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(can_do_mlock);
|
|
|
|
/*
|
|
* Mlocked pages are marked with PageMlocked() flag for efficient testing
|
|
* in vmscan and, possibly, the fault path; and to support semi-accurate
|
|
* statistics.
|
|
*
|
|
* An mlocked page [PageMlocked(page)] is unevictable. As such, it will
|
|
* be placed on the LRU "unevictable" list, rather than the [in]active lists.
|
|
* The unevictable list is an LRU sibling list to the [in]active lists.
|
|
* PageUnevictable is set to indicate the unevictable state.
|
|
*
|
|
* When lazy mlocking via vmscan, it is important to ensure that the
|
|
* vma's VM_LOCKED status is not concurrently being modified, otherwise we
|
|
* may have mlocked a page that is being munlocked. So lazy mlock must take
|
|
* the mmap_sem for read, and verify that the vma really is locked
|
|
* (see mm/rmap.c).
|
|
*/
|
|
|
|
/*
|
|
* LRU accounting for clear_page_mlock()
|
|
*/
|
|
void clear_page_mlock(struct page *page)
|
|
{
|
|
if (!TestClearPageMlocked(page))
|
|
return;
|
|
|
|
mod_zone_page_state(page_zone(page), NR_MLOCK,
|
|
-hpage_nr_pages(page));
|
|
count_vm_event(UNEVICTABLE_PGCLEARED);
|
|
if (!isolate_lru_page(page)) {
|
|
putback_lru_page(page);
|
|
} else {
|
|
/*
|
|
* We lost the race. the page already moved to evictable list.
|
|
*/
|
|
if (PageUnevictable(page))
|
|
count_vm_event(UNEVICTABLE_PGSTRANDED);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Mark page as mlocked if not already.
|
|
* If page on LRU, isolate and putback to move to unevictable list.
|
|
*/
|
|
void mlock_vma_page(struct page *page)
|
|
{
|
|
/* Serialize with page migration */
|
|
BUG_ON(!PageLocked(page));
|
|
|
|
if (!TestSetPageMlocked(page)) {
|
|
mod_zone_page_state(page_zone(page), NR_MLOCK,
|
|
hpage_nr_pages(page));
|
|
count_vm_event(UNEVICTABLE_PGMLOCKED);
|
|
if (!isolate_lru_page(page))
|
|
putback_lru_page(page);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Isolate a page from LRU with optional get_page() pin.
|
|
* Assumes lru_lock already held and page already pinned.
|
|
*/
|
|
static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
|
|
{
|
|
if (PageLRU(page)) {
|
|
struct lruvec *lruvec;
|
|
|
|
lruvec = mem_cgroup_page_lruvec(page, page_zone(page));
|
|
if (getpage)
|
|
get_page(page);
|
|
ClearPageLRU(page);
|
|
del_page_from_lru_list(page, lruvec, page_lru(page));
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Finish munlock after successful page isolation
|
|
*
|
|
* Page must be locked. This is a wrapper for try_to_munlock()
|
|
* and putback_lru_page() with munlock accounting.
|
|
*/
|
|
static void __munlock_isolated_page(struct page *page)
|
|
{
|
|
int ret = SWAP_AGAIN;
|
|
|
|
/*
|
|
* Optimization: if the page was mapped just once, that's our mapping
|
|
* and we don't need to check all the other vmas.
|
|
*/
|
|
if (page_mapcount(page) > 1)
|
|
ret = try_to_munlock(page);
|
|
|
|
/* Did try_to_unlock() succeed or punt? */
|
|
if (ret != SWAP_MLOCK)
|
|
count_vm_event(UNEVICTABLE_PGMUNLOCKED);
|
|
|
|
putback_lru_page(page);
|
|
}
|
|
|
|
/*
|
|
* Accounting for page isolation fail during munlock
|
|
*
|
|
* Performs accounting when page isolation fails in munlock. There is nothing
|
|
* else to do because it means some other task has already removed the page
|
|
* from the LRU. putback_lru_page() will take care of removing the page from
|
|
* the unevictable list, if necessary. vmscan [page_referenced()] will move
|
|
* the page back to the unevictable list if some other vma has it mlocked.
|
|
*/
|
|
static void __munlock_isolation_failed(struct page *page)
|
|
{
|
|
if (PageUnevictable(page))
|
|
__count_vm_event(UNEVICTABLE_PGSTRANDED);
|
|
else
|
|
__count_vm_event(UNEVICTABLE_PGMUNLOCKED);
|
|
}
|
|
|
|
/**
|
|
* munlock_vma_page - munlock a vma page
|
|
* @page - page to be unlocked, either a normal page or THP page head
|
|
*
|
|
* returns the size of the page as a page mask (0 for normal page,
|
|
* HPAGE_PMD_NR - 1 for THP head page)
|
|
*
|
|
* called from munlock()/munmap() path with page supposedly on the LRU.
|
|
* When we munlock a page, because the vma where we found the page is being
|
|
* munlock()ed or munmap()ed, we want to check whether other vmas hold the
|
|
* page locked so that we can leave it on the unevictable lru list and not
|
|
* bother vmscan with it. However, to walk the page's rmap list in
|
|
* try_to_munlock() we must isolate the page from the LRU. If some other
|
|
* task has removed the page from the LRU, we won't be able to do that.
|
|
* So we clear the PageMlocked as we might not get another chance. If we
|
|
* can't isolate the page, we leave it for putback_lru_page() and vmscan
|
|
* [page_referenced()/try_to_unmap()] to deal with.
|
|
*/
|
|
unsigned int munlock_vma_page(struct page *page)
|
|
{
|
|
unsigned int nr_pages;
|
|
struct zone *zone = page_zone(page);
|
|
|
|
/* For try_to_munlock() and to serialize with page migration */
|
|
BUG_ON(!PageLocked(page));
|
|
|
|
/*
|
|
* Serialize with any parallel __split_huge_page_refcount() which
|
|
* might otherwise copy PageMlocked to part of the tail pages before
|
|
* we clear it in the head page. It also stabilizes hpage_nr_pages().
|
|
*/
|
|
spin_lock_irq(&zone->lru_lock);
|
|
|
|
nr_pages = hpage_nr_pages(page);
|
|
if (!TestClearPageMlocked(page))
|
|
goto unlock_out;
|
|
|
|
__mod_zone_page_state(zone, NR_MLOCK, -nr_pages);
|
|
|
|
if (__munlock_isolate_lru_page(page, true)) {
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
__munlock_isolated_page(page);
|
|
goto out;
|
|
}
|
|
__munlock_isolation_failed(page);
|
|
|
|
unlock_out:
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
|
|
out:
|
|
return nr_pages - 1;
|
|
}
|
|
|
|
/**
|
|
* __mlock_vma_pages_range() - mlock a range of pages in the vma.
|
|
* @vma: target vma
|
|
* @start: start address
|
|
* @end: end address
|
|
* @nonblocking:
|
|
*
|
|
* This takes care of making the pages present too.
|
|
*
|
|
* return 0 on success, negative error code on error.
|
|
*
|
|
* vma->vm_mm->mmap_sem must be held.
|
|
*
|
|
* If @nonblocking is NULL, it may be held for read or write and will
|
|
* be unperturbed.
|
|
*
|
|
* If @nonblocking is non-NULL, it must held for read only and may be
|
|
* released. If it's released, *@nonblocking will be set to 0.
|
|
*/
|
|
long __mlock_vma_pages_range(struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end, int *nonblocking)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long nr_pages = (end - start) / PAGE_SIZE;
|
|
int gup_flags;
|
|
|
|
VM_BUG_ON(start & ~PAGE_MASK);
|
|
VM_BUG_ON(end & ~PAGE_MASK);
|
|
VM_BUG_ON_VMA(start < vma->vm_start, vma);
|
|
VM_BUG_ON_VMA(end > vma->vm_end, vma);
|
|
VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
|
|
|
|
gup_flags = FOLL_TOUCH | FOLL_MLOCK;
|
|
/*
|
|
* We want to touch writable mappings with a write fault in order
|
|
* to break COW, except for shared mappings because these don't COW
|
|
* and we would not want to dirty them for nothing.
|
|
*/
|
|
if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
|
|
gup_flags |= FOLL_WRITE;
|
|
|
|
/*
|
|
* We want mlock to succeed for regions that have any permissions
|
|
* other than PROT_NONE.
|
|
*/
|
|
if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
|
|
gup_flags |= FOLL_FORCE;
|
|
|
|
/*
|
|
* We made sure addr is within a VMA, so the following will
|
|
* not result in a stack expansion that recurses back here.
|
|
*/
|
|
return __get_user_pages(current, mm, start, nr_pages, gup_flags,
|
|
NULL, NULL, nonblocking);
|
|
}
|
|
|
|
/*
|
|
* convert get_user_pages() return value to posix mlock() error
|
|
*/
|
|
static int __mlock_posix_error_return(long retval)
|
|
{
|
|
if (retval == -EFAULT)
|
|
retval = -ENOMEM;
|
|
else if (retval == -ENOMEM)
|
|
retval = -EAGAIN;
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
|
|
*
|
|
* The fast path is available only for evictable pages with single mapping.
|
|
* Then we can bypass the per-cpu pvec and get better performance.
|
|
* when mapcount > 1 we need try_to_munlock() which can fail.
|
|
* when !page_evictable(), we need the full redo logic of putback_lru_page to
|
|
* avoid leaving evictable page in unevictable list.
|
|
*
|
|
* In case of success, @page is added to @pvec and @pgrescued is incremented
|
|
* in case that the page was previously unevictable. @page is also unlocked.
|
|
*/
|
|
static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec,
|
|
int *pgrescued)
|
|
{
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
|
|
if (page_mapcount(page) <= 1 && page_evictable(page)) {
|
|
pagevec_add(pvec, page);
|
|
if (TestClearPageUnevictable(page))
|
|
(*pgrescued)++;
|
|
unlock_page(page);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Putback multiple evictable pages to the LRU
|
|
*
|
|
* Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
|
|
* the pages might have meanwhile become unevictable but that is OK.
|
|
*/
|
|
static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
|
|
{
|
|
count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
|
|
/*
|
|
*__pagevec_lru_add() calls release_pages() so we don't call
|
|
* put_page() explicitly
|
|
*/
|
|
__pagevec_lru_add(pvec);
|
|
count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
|
|
}
|
|
|
|
/*
|
|
* Munlock a batch of pages from the same zone
|
|
*
|
|
* The work is split to two main phases. First phase clears the Mlocked flag
|
|
* and attempts to isolate the pages, all under a single zone lru lock.
|
|
* The second phase finishes the munlock only for pages where isolation
|
|
* succeeded.
|
|
*
|
|
* Note that the pagevec may be modified during the process.
|
|
*/
|
|
static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
|
|
{
|
|
int i;
|
|
int nr = pagevec_count(pvec);
|
|
int delta_munlocked;
|
|
struct pagevec pvec_putback;
|
|
int pgrescued = 0;
|
|
|
|
pagevec_init(&pvec_putback, 0);
|
|
|
|
/* Phase 1: page isolation */
|
|
spin_lock_irq(&zone->lru_lock);
|
|
for (i = 0; i < nr; i++) {
|
|
struct page *page = pvec->pages[i];
|
|
|
|
if (TestClearPageMlocked(page)) {
|
|
/*
|
|
* We already have pin from follow_page_mask()
|
|
* so we can spare the get_page() here.
|
|
*/
|
|
if (__munlock_isolate_lru_page(page, false))
|
|
continue;
|
|
else
|
|
__munlock_isolation_failed(page);
|
|
}
|
|
|
|
/*
|
|
* We won't be munlocking this page in the next phase
|
|
* but we still need to release the follow_page_mask()
|
|
* pin. We cannot do it under lru_lock however. If it's
|
|
* the last pin, __page_cache_release() would deadlock.
|
|
*/
|
|
pagevec_add(&pvec_putback, pvec->pages[i]);
|
|
pvec->pages[i] = NULL;
|
|
}
|
|
delta_munlocked = -nr + pagevec_count(&pvec_putback);
|
|
__mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
|
|
/* Now we can release pins of pages that we are not munlocking */
|
|
pagevec_release(&pvec_putback);
|
|
|
|
/* Phase 2: page munlock */
|
|
for (i = 0; i < nr; i++) {
|
|
struct page *page = pvec->pages[i];
|
|
|
|
if (page) {
|
|
lock_page(page);
|
|
if (!__putback_lru_fast_prepare(page, &pvec_putback,
|
|
&pgrescued)) {
|
|
/*
|
|
* Slow path. We don't want to lose the last
|
|
* pin before unlock_page()
|
|
*/
|
|
get_page(page); /* for putback_lru_page() */
|
|
__munlock_isolated_page(page);
|
|
unlock_page(page);
|
|
put_page(page); /* from follow_page_mask() */
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Phase 3: page putback for pages that qualified for the fast path
|
|
* This will also call put_page() to return pin from follow_page_mask()
|
|
*/
|
|
if (pagevec_count(&pvec_putback))
|
|
__putback_lru_fast(&pvec_putback, pgrescued);
|
|
}
|
|
|
|
/*
|
|
* Fill up pagevec for __munlock_pagevec using pte walk
|
|
*
|
|
* The function expects that the struct page corresponding to @start address is
|
|
* a non-TPH page already pinned and in the @pvec, and that it belongs to @zone.
|
|
*
|
|
* The rest of @pvec is filled by subsequent pages within the same pmd and same
|
|
* zone, as long as the pte's are present and vm_normal_page() succeeds. These
|
|
* pages also get pinned.
|
|
*
|
|
* Returns the address of the next page that should be scanned. This equals
|
|
* @start + PAGE_SIZE when no page could be added by the pte walk.
|
|
*/
|
|
static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
|
|
struct vm_area_struct *vma, int zoneid, unsigned long start,
|
|
unsigned long end)
|
|
{
|
|
pte_t *pte;
|
|
spinlock_t *ptl;
|
|
|
|
/*
|
|
* Initialize pte walk starting at the already pinned page where we
|
|
* are sure that there is a pte, as it was pinned under the same
|
|
* mmap_sem write op.
|
|
*/
|
|
pte = get_locked_pte(vma->vm_mm, start, &ptl);
|
|
/* Make sure we do not cross the page table boundary */
|
|
end = pgd_addr_end(start, end);
|
|
end = pud_addr_end(start, end);
|
|
end = pmd_addr_end(start, end);
|
|
|
|
/* The page next to the pinned page is the first we will try to get */
|
|
start += PAGE_SIZE;
|
|
while (start < end) {
|
|
struct page *page = NULL;
|
|
pte++;
|
|
if (pte_present(*pte))
|
|
page = vm_normal_page(vma, start, *pte);
|
|
/*
|
|
* Break if page could not be obtained or the page's node+zone does not
|
|
* match
|
|
*/
|
|
if (!page || page_zone_id(page) != zoneid)
|
|
break;
|
|
|
|
get_page(page);
|
|
/*
|
|
* Increase the address that will be returned *before* the
|
|
* eventual break due to pvec becoming full by adding the page
|
|
*/
|
|
start += PAGE_SIZE;
|
|
if (pagevec_add(pvec, page) == 0)
|
|
break;
|
|
}
|
|
pte_unmap_unlock(pte, ptl);
|
|
return start;
|
|
}
|
|
|
|
/*
|
|
* munlock_vma_pages_range() - munlock all pages in the vma range.'
|
|
* @vma - vma containing range to be munlock()ed.
|
|
* @start - start address in @vma of the range
|
|
* @end - end of range in @vma.
|
|
*
|
|
* For mremap(), munmap() and exit().
|
|
*
|
|
* Called with @vma VM_LOCKED.
|
|
*
|
|
* Returns with VM_LOCKED cleared. Callers must be prepared to
|
|
* deal with this.
|
|
*
|
|
* We don't save and restore VM_LOCKED here because pages are
|
|
* still on lru. In unmap path, pages might be scanned by reclaim
|
|
* and re-mlocked by try_to_{munlock|unmap} before we unmap and
|
|
* free them. This will result in freeing mlocked pages.
|
|
*/
|
|
void munlock_vma_pages_range(struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
vma->vm_flags &= ~VM_LOCKED;
|
|
|
|
while (start < end) {
|
|
struct page *page = NULL;
|
|
unsigned int page_mask;
|
|
unsigned long page_increm;
|
|
struct pagevec pvec;
|
|
struct zone *zone;
|
|
int zoneid;
|
|
|
|
pagevec_init(&pvec, 0);
|
|
/*
|
|
* Although FOLL_DUMP is intended for get_dump_page(),
|
|
* it just so happens that its special treatment of the
|
|
* ZERO_PAGE (returning an error instead of doing get_page)
|
|
* suits munlock very well (and if somehow an abnormal page
|
|
* has sneaked into the range, we won't oops here: great).
|
|
*/
|
|
page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP,
|
|
&page_mask);
|
|
|
|
if (page && !IS_ERR(page)) {
|
|
if (PageTransHuge(page)) {
|
|
lock_page(page);
|
|
/*
|
|
* Any THP page found by follow_page_mask() may
|
|
* have gotten split before reaching
|
|
* munlock_vma_page(), so we need to recompute
|
|
* the page_mask here.
|
|
*/
|
|
page_mask = munlock_vma_page(page);
|
|
unlock_page(page);
|
|
put_page(page); /* follow_page_mask() */
|
|
} else {
|
|
/*
|
|
* Non-huge pages are handled in batches via
|
|
* pagevec. The pin from follow_page_mask()
|
|
* prevents them from collapsing by THP.
|
|
*/
|
|
pagevec_add(&pvec, page);
|
|
zone = page_zone(page);
|
|
zoneid = page_zone_id(page);
|
|
|
|
/*
|
|
* Try to fill the rest of pagevec using fast
|
|
* pte walk. This will also update start to
|
|
* the next page to process. Then munlock the
|
|
* pagevec.
|
|
*/
|
|
start = __munlock_pagevec_fill(&pvec, vma,
|
|
zoneid, start, end);
|
|
__munlock_pagevec(&pvec, zone);
|
|
goto next;
|
|
}
|
|
}
|
|
/* It's a bug to munlock in the middle of a THP page */
|
|
VM_BUG_ON((start >> PAGE_SHIFT) & page_mask);
|
|
page_increm = 1 + page_mask;
|
|
start += page_increm * PAGE_SIZE;
|
|
next:
|
|
cond_resched();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* mlock_fixup - handle mlock[all]/munlock[all] requests.
|
|
*
|
|
* Filters out "special" vmas -- VM_LOCKED never gets set for these, and
|
|
* munlock is a no-op. However, for some special vmas, we go ahead and
|
|
* populate the ptes.
|
|
*
|
|
* For vmas that pass the filters, merge/split as appropriate.
|
|
*/
|
|
static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end, vm_flags_t newflags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgoff_t pgoff;
|
|
int nr_pages;
|
|
int ret = 0;
|
|
int lock = !!(newflags & VM_LOCKED);
|
|
|
|
if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
|
|
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm))
|
|
goto out; /* don't set VM_LOCKED, don't count */
|
|
|
|
pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
|
|
*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
|
|
vma->vm_file, pgoff, vma_policy(vma));
|
|
if (*prev) {
|
|
vma = *prev;
|
|
goto success;
|
|
}
|
|
|
|
if (start != vma->vm_start) {
|
|
ret = split_vma(mm, vma, start, 1);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
if (end != vma->vm_end) {
|
|
ret = split_vma(mm, vma, end, 0);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
success:
|
|
/*
|
|
* Keep track of amount of locked VM.
|
|
*/
|
|
nr_pages = (end - start) >> PAGE_SHIFT;
|
|
if (!lock)
|
|
nr_pages = -nr_pages;
|
|
mm->locked_vm += nr_pages;
|
|
|
|
/*
|
|
* vm_flags is protected by the mmap_sem held in write mode.
|
|
* It's okay if try_to_unmap_one unmaps a page just after we
|
|
* set VM_LOCKED, __mlock_vma_pages_range will bring it back.
|
|
*/
|
|
|
|
if (lock)
|
|
vma->vm_flags = newflags;
|
|
else
|
|
munlock_vma_pages_range(vma, start, end);
|
|
|
|
out:
|
|
*prev = vma;
|
|
return ret;
|
|
}
|
|
|
|
static int do_mlock(unsigned long start, size_t len, int on)
|
|
{
|
|
unsigned long nstart, end, tmp;
|
|
struct vm_area_struct * vma, * prev;
|
|
int error;
|
|
|
|
VM_BUG_ON(start & ~PAGE_MASK);
|
|
VM_BUG_ON(len != PAGE_ALIGN(len));
|
|
end = start + len;
|
|
if (end < start)
|
|
return -EINVAL;
|
|
if (end == start)
|
|
return 0;
|
|
vma = find_vma(current->mm, start);
|
|
if (!vma || vma->vm_start > start)
|
|
return -ENOMEM;
|
|
|
|
prev = vma->vm_prev;
|
|
if (start > vma->vm_start)
|
|
prev = vma;
|
|
|
|
for (nstart = start ; ; ) {
|
|
vm_flags_t newflags;
|
|
|
|
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
|
|
|
|
newflags = vma->vm_flags & ~VM_LOCKED;
|
|
if (on)
|
|
newflags |= VM_LOCKED;
|
|
|
|
tmp = vma->vm_end;
|
|
if (tmp > end)
|
|
tmp = end;
|
|
error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
|
|
if (error)
|
|
break;
|
|
nstart = tmp;
|
|
if (nstart < prev->vm_end)
|
|
nstart = prev->vm_end;
|
|
if (nstart >= end)
|
|
break;
|
|
|
|
vma = prev->vm_next;
|
|
if (!vma || vma->vm_start != nstart) {
|
|
error = -ENOMEM;
|
|
break;
|
|
}
|
|
}
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* __mm_populate - populate and/or mlock pages within a range of address space.
|
|
*
|
|
* This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
|
|
* flags. VMAs must be already marked with the desired vm_flags, and
|
|
* mmap_sem must not be held.
|
|
*/
|
|
int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long end, nstart, nend;
|
|
struct vm_area_struct *vma = NULL;
|
|
int locked = 0;
|
|
long ret = 0;
|
|
|
|
VM_BUG_ON(start & ~PAGE_MASK);
|
|
VM_BUG_ON(len != PAGE_ALIGN(len));
|
|
end = start + len;
|
|
|
|
for (nstart = start; nstart < end; nstart = nend) {
|
|
/*
|
|
* We want to fault in pages for [nstart; end) address range.
|
|
* Find first corresponding VMA.
|
|
*/
|
|
if (!locked) {
|
|
locked = 1;
|
|
down_read(&mm->mmap_sem);
|
|
vma = find_vma(mm, nstart);
|
|
} else if (nstart >= vma->vm_end)
|
|
vma = vma->vm_next;
|
|
if (!vma || vma->vm_start >= end)
|
|
break;
|
|
/*
|
|
* Set [nstart; nend) to intersection of desired address
|
|
* range with the first VMA. Also, skip undesirable VMA types.
|
|
*/
|
|
nend = min(end, vma->vm_end);
|
|
if (vma->vm_flags & (VM_IO | VM_PFNMAP))
|
|
continue;
|
|
if (nstart < vma->vm_start)
|
|
nstart = vma->vm_start;
|
|
/*
|
|
* Now fault in a range of pages. __mlock_vma_pages_range()
|
|
* double checks the vma flags, so that it won't mlock pages
|
|
* if the vma was already munlocked.
|
|
*/
|
|
ret = __mlock_vma_pages_range(vma, nstart, nend, &locked);
|
|
if (ret < 0) {
|
|
if (ignore_errors) {
|
|
ret = 0;
|
|
continue; /* continue at next VMA */
|
|
}
|
|
ret = __mlock_posix_error_return(ret);
|
|
break;
|
|
}
|
|
nend = nstart + ret * PAGE_SIZE;
|
|
ret = 0;
|
|
}
|
|
if (locked)
|
|
up_read(&mm->mmap_sem);
|
|
return ret; /* 0 or negative error code */
|
|
}
|
|
|
|
SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
|
|
{
|
|
unsigned long locked;
|
|
unsigned long lock_limit;
|
|
int error = -ENOMEM;
|
|
|
|
if (!can_do_mlock())
|
|
return -EPERM;
|
|
|
|
lru_add_drain_all(); /* flush pagevec */
|
|
|
|
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
|
|
start &= PAGE_MASK;
|
|
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
lock_limit >>= PAGE_SHIFT;
|
|
locked = len >> PAGE_SHIFT;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
|
|
locked += current->mm->locked_vm;
|
|
|
|
/* check against resource limits */
|
|
if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
|
|
error = do_mlock(start, len, 1);
|
|
|
|
up_write(¤t->mm->mmap_sem);
|
|
if (!error)
|
|
error = __mm_populate(start, len, 0);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
|
|
{
|
|
int ret;
|
|
|
|
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
|
|
start &= PAGE_MASK;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
ret = do_mlock(start, len, 0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int do_mlockall(int flags)
|
|
{
|
|
struct vm_area_struct * vma, * prev = NULL;
|
|
|
|
if (flags & MCL_FUTURE)
|
|
current->mm->def_flags |= VM_LOCKED;
|
|
else
|
|
current->mm->def_flags &= ~VM_LOCKED;
|
|
if (flags == MCL_FUTURE)
|
|
goto out;
|
|
|
|
for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
|
|
vm_flags_t newflags;
|
|
|
|
newflags = vma->vm_flags & ~VM_LOCKED;
|
|
if (flags & MCL_CURRENT)
|
|
newflags |= VM_LOCKED;
|
|
|
|
/* Ignore errors */
|
|
mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
|
|
cond_resched_rcu_qs();
|
|
}
|
|
out:
|
|
return 0;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(mlockall, int, flags)
|
|
{
|
|
unsigned long lock_limit;
|
|
int ret = -EINVAL;
|
|
|
|
if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
|
|
goto out;
|
|
|
|
ret = -EPERM;
|
|
if (!can_do_mlock())
|
|
goto out;
|
|
|
|
if (flags & MCL_CURRENT)
|
|
lru_add_drain_all(); /* flush pagevec */
|
|
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
lock_limit >>= PAGE_SHIFT;
|
|
|
|
ret = -ENOMEM;
|
|
down_write(¤t->mm->mmap_sem);
|
|
|
|
if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
|
|
capable(CAP_IPC_LOCK))
|
|
ret = do_mlockall(flags);
|
|
up_write(¤t->mm->mmap_sem);
|
|
if (!ret && (flags & MCL_CURRENT))
|
|
mm_populate(0, TASK_SIZE);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE0(munlockall)
|
|
{
|
|
int ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
ret = do_mlockall(0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
|
|
* shm segments) get accounted against the user_struct instead.
|
|
*/
|
|
static DEFINE_SPINLOCK(shmlock_user_lock);
|
|
|
|
int user_shm_lock(size_t size, struct user_struct *user)
|
|
{
|
|
unsigned long lock_limit, locked;
|
|
int allowed = 0;
|
|
|
|
locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
if (lock_limit == RLIM_INFINITY)
|
|
allowed = 1;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
spin_lock(&shmlock_user_lock);
|
|
if (!allowed &&
|
|
locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
|
|
goto out;
|
|
get_uid(user);
|
|
user->locked_shm += locked;
|
|
allowed = 1;
|
|
out:
|
|
spin_unlock(&shmlock_user_lock);
|
|
return allowed;
|
|
}
|
|
|
|
void user_shm_unlock(size_t size, struct user_struct *user)
|
|
{
|
|
spin_lock(&shmlock_user_lock);
|
|
user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
spin_unlock(&shmlock_user_lock);
|
|
free_uid(user);
|
|
}
|