percpu: make pcpu_alloc_area() capable of allocating only from populated areas (a16037c8) · Commits · 戴 / test

mm/percpu.c

+58 −7

Original line number	Diff line number	Diff line
		@@ -399,11 +399,61 @@ out_unlock:
		return 0;
		}

		/**
		* pcpu_fit_in_area - try to fit the requested allocation in a candidate area
		* @chunk: chunk the candidate area belongs to
		* @off: the offset to the start of the candidate area
		* @this_size: the size of the candidate area
		* @size: the size of the target allocation
		* @align: the alignment of the target allocation
		* @pop_only: only allocate from already populated region
		*
		* We're trying to allocate @size bytes aligned at @align. @chunk's area
		* at @off sized @this_size is a candidate. This function determines
		* whether the target allocation fits in the candidate area and returns the
		* number of bytes to pad after @off. If the target area doesn't fit, -1
		* is returned.
		*
		* If @pop_only is %true, this function only considers the already
		* populated part of the candidate area.
		*/
		static int pcpu_fit_in_area(struct pcpu_chunk *chunk, int off, int this_size,
		int size, int align, bool pop_only)
		{
		int cand_off = off;

		while (true) {
		int head = ALIGN(cand_off, align) - off;
		int page_start, page_end, rs, re;

		if (this_size < head + size)
		return -1;

		if (!pop_only)
		return head;

		/*
		* If the first unpopulated page is beyond the end of the
		* allocation, the whole allocation is populated;
		* otherwise, retry from the end of the unpopulated area.
		*/
		page_start = PFN_DOWN(head + off);
		page_end = PFN_UP(head + off + size);

		rs = page_start;
		pcpu_next_unpop(chunk, &rs, &re, PFN_UP(off + this_size));
		if (rs >= page_end)
		return head;
		cand_off = re * PAGE_SIZE;
		}
		}

		/**
		* pcpu_alloc_area - allocate area from a pcpu_chunk
		* @chunk: chunk of interest
		* @size: wanted size in bytes
		* @align: wanted align
		* @pop_only: allocate only from the populated area
		*
		* Try to allocate @size bytes area aligned at @align from @chunk.
		* Note that this function only allocates the offset. It doesn't
		@@ -418,7 +468,8 @@ out_unlock:
		* Allocated offset in @chunk on success, -1 if no matching area is
		* found.
		*/
		static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align)
		static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align,
		bool pop_only)
		{
		int oslot = pcpu_chunk_slot(chunk);
		int max_contig = 0;
		@@ -434,11 +485,11 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align)
		if (off & 1)
		continue;

		/* extra for alignment requirement */
		head = ALIGN(off, align) - off;

		this_size = (p[1] & ~1) - off;
		if (this_size < head + size) {

		head = pcpu_fit_in_area(chunk, off, this_size, size, align,
		pop_only);
		if (head < 0) {
		if (!seen_free) {
		chunk->first_free = i;
		seen_free = true;
		@@ -730,7 +781,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
		spin_lock_irqsave(&pcpu_lock, flags);
		}

		off = pcpu_alloc_area(chunk, size, align);
		off = pcpu_alloc_area(chunk, size, align, false);
		if (off >= 0)
		goto area_found;

		@@ -761,7 +812,7 @@ restart:
		goto restart;
		}

		off = pcpu_alloc_area(chunk, size, align);
		off = pcpu_alloc_area(chunk, size, align, false);
		if (off >= 0)
		goto area_found;
		}

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