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fs/proc/task_mmu.c: make the task_mmu walk_page_range() limit in clear_refs_write() obvious

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Trying to walk all of virtual memory requires architecture specific
knowledge.  On x86_64, addresses must be sign extended from bit 48,
whereas on arm64 the top VA_BITS of address space have their own set of
page tables.

clear_refs_write() calls walk_page_range() on the range 0 to ~0UL, it
provides a test_walk() callback that only expects to be walking over
VMAs.  Currently walk_pmd_range() will skip memory regions that don't
have a VMA, reporting them as a hole.

As this call only expects to walk user address space, make it walk 0 to
'highest_vm_end'.

Link: http://lkml.kernel.org/r/1472655792-22439-1-git-send-email-james.morse@arm.com
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
James Morse 2016-10-07 17:00:06 -07:00 committed by Linus Torvalds
parent 03e86dba5b
commit 0f30206bf2
1 changed files with 1 additions and 1 deletions
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2
fs/proc/task_mmu.c
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@ -1070,7 +1070,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
}
mmu_notifier_invalidate_range_start(mm, 0, -1);
}
walk_page_range(0, ~0UL, &clear_refs_walk);
walk_page_range(0, mm->highest_vm_end, &clear_refs_walk);
if (type == CLEAR_REFS_SOFT_DIRTY)
mmu_notifier_invalidate_range_end(mm, 0, -1);
flush_tlb_mm(mm);