Commit 9d3af4b4 authored by Will Deacon's avatar Will Deacon
Browse files

mm: Pass 'address' to map to do_set_pte() and drop FAULT_FLAG_PREFAULT 



Rather than modifying the 'address' field of the 'struct vm_fault'
passed to do_set_pte(), leave that to identify the real faulting address
and pass in the virtual address to be mapped by the new pte as a
separate argument.

This makes FAULT_FLAG_PREFAULT redundant, as a prefault entry can be
identified simply by comparing the new address parameter with the
faulting address, so remove the redundant flag at the same time.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 742d3372

include/linux/mm.h

+2 −5
Original line number Diff line number Diff line
@@ -434,7 +434,6 @@ extern pgprot_t protection_map[16]; 
 * @FAULT_FLAG_REMOTE: The fault is not for current task/mm.

 * @FAULT_FLAG_INSTRUCTION: The fault was during an instruction fetch.

 * @FAULT_FLAG_INTERRUPTIBLE: The fault can be interrupted by non-fatal signals.

 * @FAULT_FLAG_PREFAULT: Fault was a prefault.

 *

 * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify

 * whether we would allow page faults to retry by specifying these two
@@ -465,7 +464,6 @@ extern pgprot_t protection_map[16]; 
#define FAULT_FLAG_REMOTE			0x80

#define FAULT_FLAG_INSTRUCTION  		0x100

#define FAULT_FLAG_INTERRUPTIBLE		0x200

#define FAULT_FLAG_PREFAULT			0x400



/*

 * The default fault flags that should be used by most of the
@@ -503,8 +501,7 @@ static inline bool fault_flag_allow_retry_first(unsigned int flags) 
	{ FAULT_FLAG_USER,		"USER" }, \

	{ FAULT_FLAG_REMOTE,		"REMOTE" }, \

	{ FAULT_FLAG_INSTRUCTION,	"INSTRUCTION" }, \

	{ FAULT_FLAG_INTERRUPTIBLE,	"INTERRUPTIBLE" }, \

	{ FAULT_FLAG_PREFAULT,		"PREFAULT" }

	{ FAULT_FLAG_INTERRUPTIBLE,	"INTERRUPTIBLE" }



/*

 * vm_fault is filled by the pagefault handler and passed to the vma's
@@ -995,7 +992,7 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 
}



vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page);

void do_set_pte(struct vm_fault *vmf, struct page *page);

void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr);



vm_fault_t finish_fault(struct vm_fault *vmf);

vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);

mm/filemap.c

+7 −14
Original line number Diff line number Diff line
@@ -3018,8 +3018,7 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, 
	struct file *file = vma->vm_file;

	struct address_space *mapping = file->f_mapping;

	pgoff_t last_pgoff = start_pgoff;

	unsigned long address = vmf->address;

	unsigned long flags = vmf->flags;

	unsigned long addr;

	XA_STATE(xas, &mapping->i_pages, start_pgoff);

	struct page *head, *page;

	unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
@@ -3035,8 +3034,8 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, 
		goto out;

	}



	vmf->address = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT);

	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl);

	addr = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT);

	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);

	do {

		page = find_subpage(head, xas.xa_index);

		if (PageHWPoison(page))
@@ -3045,7 +3044,7 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, 
		if (mmap_miss > 0)

			mmap_miss--;



		vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT;

		addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT;

		vmf->pte += xas.xa_index - last_pgoff;

		last_pgoff = xas.xa_index;
@@ -3053,16 +3052,12 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, 
			goto unlock;



		/* We're about to handle the fault */

		if (vmf->address == address) {

			vmf->flags &= ~FAULT_FLAG_PREFAULT;

		if (vmf->address == addr)

			ret = VM_FAULT_NOPAGE;

		} else {

			vmf->flags |= FAULT_FLAG_PREFAULT;

		}



		do_set_pte(vmf, page);

		do_set_pte(vmf, page, addr);

		/* no need to invalidate: a not-present page won't be cached */

		update_mmu_cache(vma, vmf->address, vmf->pte);

		update_mmu_cache(vma, addr, vmf->pte);

		unlock_page(head);

		continue;

unlock:
@@ -3072,8 +3067,6 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, 
	pte_unmap_unlock(vmf->pte, vmf->ptl);

out:

	rcu_read_unlock();

	vmf->flags = flags;

	vmf->address = address;

	WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);

	return ret;

}

mm/memory.c

+5 −5
Original line number Diff line number Diff line
@@ -3733,11 +3733,11 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) 
}

#endif



void do_set_pte(struct vm_fault *vmf, struct page *page)

void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)

{

	struct vm_area_struct *vma = vmf->vma;

	bool write = vmf->flags & FAULT_FLAG_WRITE;

	bool prefault = vmf->flags & FAULT_FLAG_PREFAULT;

	bool prefault = vmf->address != addr;

	pte_t entry;



	flush_icache_page(vma, page);
@@ -3753,13 +3753,13 @@ void do_set_pte(struct vm_fault *vmf, struct page *page) 
	/* copy-on-write page */

	if (write && !(vma->vm_flags & VM_SHARED)) {

		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);

		page_add_new_anon_rmap(page, vma, vmf->address, false);

		page_add_new_anon_rmap(page, vma, addr, false);

		lru_cache_add_inactive_or_unevictable(page, vma);

	} else {

		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));

		page_add_file_rmap(page, false);

	}

	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);

	set_pte_at(vma->vm_mm, addr, vmf->pte, entry);

}



/**
@@ -3819,7 +3819,7 @@ vm_fault_t finish_fault(struct vm_fault *vmf) 
	ret = 0;

	/* Re-check under ptl */

	if (likely(pte_none(*vmf->pte)))

		do_set_pte(vmf, page);

		do_set_pte(vmf, page, vmf->address);

	else

		ret = VM_FAULT_NOPAGE;