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[PATCH] mm: copy_pte_range progress fix
My latency breaking in copy_pte_range didn't work as intended: instead of checking at regularish intervals, after the first interval it checked every time around the loop, too impatient to be preempted. Fix that. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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parent
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commit
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14
mm/memory.c
14
mm/memory.c
@ -410,7 +410,7 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
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{
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pte_t *src_pte, *dst_pte;
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unsigned long vm_flags = vma->vm_flags;
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int progress;
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int progress = 0;
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again:
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dst_pte = pte_alloc_map(dst_mm, dst_pmd, addr);
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@ -418,17 +418,19 @@ again:
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return -ENOMEM;
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src_pte = pte_offset_map_nested(src_pmd, addr);
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progress = 0;
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spin_lock(&src_mm->page_table_lock);
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do {
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/*
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* We are holding two locks at this point - either of them
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* could generate latencies in another task on another CPU.
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*/
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if (progress >= 32 && (need_resched() ||
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need_lockbreak(&src_mm->page_table_lock) ||
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need_lockbreak(&dst_mm->page_table_lock)))
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break;
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if (progress >= 32) {
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progress = 0;
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if (need_resched() ||
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need_lockbreak(&src_mm->page_table_lock) ||
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need_lockbreak(&dst_mm->page_table_lock))
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break;
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}
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if (pte_none(*src_pte)) {
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progress++;
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continue;
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