Commit b8aa9d9d authored by Wei Yang's avatar Wei Yang Committed by Linus Torvalds
Browse files

mm/mremap: it is sure to have enough space when extent meets requirement 



Patch series "mm/mremap: cleanup move_page_tables() a little", v5.

move_page_tables() tries to move page table by PMD or PTE.

The root reason is if it tries to move PMD, both old and new range should
be PMD aligned.  But current code calculate old range and new range
separately.  This leads to some redundant check and calculation.

This cleanup tries to consolidate the range check in one place to reduce
some extra range handling.

This patch (of 3):

old_end is passed to these two functions to check whether there is enough
space to do the move, while this check is done before invoking these
functions.

These two functions only would be invoked when extent meets the
requirement and there is one check before invoking these functions:

    if (extent > old_end - old_addr)
        extent = old_end - old_addr;

This implies (old_end - old_addr) won't fail the check in these two
functions.

Signed-off-by: default avatarWei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Tested-by: default avatarDmitry Osipenko <digetx@gmail.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Thomas Hellstrom (VMware) <thomas_os@shipmail.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Link: http://lkml.kernel.org/r/20200710092835.56368-1-richard.weiyang@linux.alibaba.com
Link: http://lkml.kernel.org/r/20200710092835.56368-2-richard.weiyang@linux.alibaba.com
Link: http://lkml.kernel.org/r/20200708095028.41706-1-richard.weiyang@linux.alibaba.com
Link: http://lkml.kernel.org/r/20200708095028.41706-2-richard.weiyang@linux.alibaba.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 45e55300

include/linux/huge_mm.h

+1 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 
			unsigned long addr, unsigned long end,

			unsigned char *vec);

extern bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,

			 unsigned long new_addr, unsigned long old_end,

			 unsigned long new_addr,

			 pmd_t *old_pmd, pmd_t *new_pmd);

extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,

			unsigned long addr, pgprot_t newprot,

mm/huge_memory.c

+2 −5
Original line number Diff line number Diff line
@@ -1722,17 +1722,14 @@ static pmd_t move_soft_dirty_pmd(pmd_t pmd) 
}



bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,

		  unsigned long new_addr, unsigned long old_end,

		  pmd_t *old_pmd, pmd_t *new_pmd)

		  unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)

{

	spinlock_t *old_ptl, *new_ptl;

	pmd_t pmd;

	struct mm_struct *mm = vma->vm_mm;

	bool force_flush = false;



	if ((old_addr & ~HPAGE_PMD_MASK) ||

	    (new_addr & ~HPAGE_PMD_MASK) ||

	    old_end - old_addr < HPAGE_PMD_SIZE)

	if ((old_addr & ~HPAGE_PMD_MASK) || (new_addr & ~HPAGE_PMD_MASK))

		return false;



	/*

mm/mremap.c

+4 −6
Original line number Diff line number Diff line
@@ -193,15 +193,13 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, 


#ifdef CONFIG_HAVE_MOVE_PMD

static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,

		  unsigned long new_addr, unsigned long old_end,

		  pmd_t *old_pmd, pmd_t *new_pmd)

		  unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)

{

	spinlock_t *old_ptl, *new_ptl;

	struct mm_struct *mm = vma->vm_mm;

	pmd_t pmd;



	if ((old_addr & ~PMD_MASK) || (new_addr & ~PMD_MASK)

	    || old_end - old_addr < PMD_SIZE)

	if ((old_addr & ~PMD_MASK) || (new_addr & ~PMD_MASK))

		return false;



	/*
@@ -292,7 +290,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, 
				if (need_rmap_locks)

					take_rmap_locks(vma);

				moved = move_huge_pmd(vma, old_addr, new_addr,

						    old_end, old_pmd, new_pmd);

						      old_pmd, new_pmd);

				if (need_rmap_locks)

					drop_rmap_locks(vma);

				if (moved)
@@ -312,7 +310,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, 
			if (need_rmap_locks)

				take_rmap_locks(vma);

			moved = move_normal_pmd(vma, old_addr, new_addr,

					old_end, old_pmd, new_pmd);

						old_pmd, new_pmd);

			if (need_rmap_locks)

				drop_rmap_locks(vma);

			if (moved)

CRA Git | Maintained and supported by SUSTech CRA and CCSE