Commit d10e63f2 authored by Mel Gorman's avatar Mel Gorman

mm: numa: Create basic numa page hinting infrastructure

Note: This patch started as "mm/mpol: Create special PROT_NONE
	infrastructure" and preserves the basic idea but steals *very*
	heavily from "autonuma: numa hinting page faults entry points" for
	the actual fault handlers without the migration parts.	The end
	result is barely recognisable as either patch so all Signed-off
	and Reviewed-bys are dropped. If Peter, Ingo and Andrea are ok with
	this version, I will re-add the signed-offs-by to reflect the history.

In order to facilitate a lazy -- fault driven -- migration of pages, create
a special transient PAGE_NUMA variant, we can then use the 'spurious'
protection faults to drive our migrations from.

The meaning of PAGE_NUMA depends on the architecture but on x86 it is
effectively PROT_NONE. Actual PROT_NONE mappings will not generate these
NUMA faults for the reason that the page fault code checks the permission on
the VMA (and will throw a segmentation fault on actual PROT_NONE mappings),
before it ever calls handle_mm_fault.

[dhillf@gmail.com: Fix typo]
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
parent 1ba6e0b5
......@@ -159,6 +159,10 @@ static inline struct page *compound_trans_head(struct page *page)
}
return page;
}
extern int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,
pmd_t pmd, pmd_t *pmdp);
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
#define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
......@@ -195,6 +199,12 @@ static inline int pmd_trans_huge_lock(pmd_t *pmd,
{
return 0;
}
static inline int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,
pmd_t pmd, pmd_t *pmdp)
{
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif /* _LINUX_HUGE_MM_H */
......@@ -1018,6 +1018,28 @@ out:
return page;
}
/* NUMA hinting page fault entry point for trans huge pmds */
int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,
pmd_t pmd, pmd_t *pmdp)
{
struct page *page;
unsigned long haddr = addr & HPAGE_PMD_MASK;
spin_lock(&mm->page_table_lock);
if (unlikely(!pmd_same(pmd, *pmdp)))
goto out_unlock;
page = pmd_page(pmd);
pmd = pmd_mknonnuma(pmd);
set_pmd_at(mm, haddr, pmdp, pmd);
VM_BUG_ON(pmd_numa(*pmdp));
update_mmu_cache_pmd(vma, addr, pmdp);
out_unlock:
spin_unlock(&mm->page_table_lock);
return 0;
}
int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
pmd_t *pmd, unsigned long addr)
{
......
......@@ -3448,6 +3448,103 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
}
int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
struct page *page;
spinlock_t *ptl;
/*
* The "pte" at this point cannot be used safely without
* validation through pte_unmap_same(). It's of NUMA type but
* the pfn may be screwed if the read is non atomic.
*
* ptep_modify_prot_start is not called as this is clearing
* the _PAGE_NUMA bit and it is not really expected that there
* would be concurrent hardware modifications to the PTE.
*/
ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
if (unlikely(!pte_same(*ptep, pte)))
goto out_unlock;
pte = pte_mknonnuma(pte);
set_pte_at(mm, addr, ptep, pte);
update_mmu_cache(vma, addr, ptep);
page = vm_normal_page(vma, addr, pte);
if (!page) {
pte_unmap_unlock(ptep, ptl);
return 0;
}
out_unlock:
pte_unmap_unlock(ptep, ptl);
return 0;
}
/* NUMA hinting page fault entry point for regular pmds */
#ifdef CONFIG_NUMA_BALANCING
static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmdp)
{
pmd_t pmd;
pte_t *pte, *orig_pte;
unsigned long _addr = addr & PMD_MASK;
unsigned long offset;
spinlock_t *ptl;
bool numa = false;
spin_lock(&mm->page_table_lock);
pmd = *pmdp;
if (pmd_numa(pmd)) {
set_pmd_at(mm, _addr, pmdp, pmd_mknonnuma(pmd));
numa = true;
}
spin_unlock(&mm->page_table_lock);
if (!numa)
return 0;
/* we're in a page fault so some vma must be in the range */
BUG_ON(!vma);
BUG_ON(vma->vm_start >= _addr + PMD_SIZE);
offset = max(_addr, vma->vm_start) & ~PMD_MASK;
VM_BUG_ON(offset >= PMD_SIZE);
orig_pte = pte = pte_offset_map_lock(mm, pmdp, _addr, &ptl);
pte += offset >> PAGE_SHIFT;
for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) {
pte_t pteval = *pte;
struct page *page;
if (!pte_present(pteval))
continue;
if (!pte_numa(pteval))
continue;
if (addr >= vma->vm_end) {
vma = find_vma(mm, addr);
/* there's a pte present so there must be a vma */
BUG_ON(!vma);
BUG_ON(addr < vma->vm_start);
}
if (pte_numa(pteval)) {
pteval = pte_mknonnuma(pteval);
set_pte_at(mm, addr, pte, pteval);
}
page = vm_normal_page(vma, addr, pteval);
if (unlikely(!page))
continue;
}
pte_unmap_unlock(orig_pte, ptl);
return 0;
}
#else
static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pmd_t *pmdp)
{
BUG();
}
#endif /* CONFIG_NUMA_BALANCING */
/*
* These routines also need to handle stuff like marking pages dirty
* and/or accessed for architectures that don't do it in hardware (most
......@@ -3486,6 +3583,9 @@ int handle_pte_fault(struct mm_struct *mm,
pte, pmd, flags, entry);
}
if (pte_numa(entry))
return do_numa_page(mm, vma, address, entry, pte, pmd);
ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
if (unlikely(!pte_same(*pte, entry)))
......@@ -3554,9 +3654,11 @@ retry:
barrier();
if (pmd_trans_huge(orig_pmd)) {
if (flags & FAULT_FLAG_WRITE &&
!pmd_write(orig_pmd) &&
!pmd_trans_splitting(orig_pmd)) {
if (pmd_numa(*pmd))
return do_huge_pmd_numa_page(mm, address,
orig_pmd, pmd);
if ((flags & FAULT_FLAG_WRITE) && !pmd_write(orig_pmd)) {
ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
orig_pmd);
/*
......@@ -3568,10 +3670,14 @@ retry:
goto retry;
return ret;
}
return 0;
}
}
if (pmd_numa(*pmd))
return do_pmd_numa_page(mm, vma, address, pmd);
/*
* Use __pte_alloc instead of pte_alloc_map, because we can't
* run pte_offset_map on the pmd, if an huge pmd could
......
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