From 481ebd0d76b501c5772f702ae31e55350c0858a3 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 20 Aug 2008 14:09:15 -0700 Subject: [PATCH] bootmem: fix aligning of node-relative indexes and offsets Absolute alignment requirements may never be applied to node-relative offsets. Andreas Herrmann spotted this flaw when a bootmem allocation on an unaligned node was itself not aligned because the combination of an unaligned node with an aligned offset into that node is not garuanteed to be aligned itself. This patch introduces two helper functions that align a node-relative index or offset with respect to the node's starting address so that the absolute PFN or virtual address that results from combining the two satisfies the requested alignment. Then all the broken ALIGN()s in alloc_bootmem_core() are replaced by these helpers. Signed-off-by: Johannes Weiner Reported-by: Andreas Herrmann Debugged-by: Andreas Herrmann Reviewed-by: Andreas Herrmann Tested-by: Andreas Herrmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/bootmem.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) diff --git a/mm/bootmem.c b/mm/bootmem.c index e023c68..ad8eec6 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -405,6 +405,29 @@ int __init reserve_bootmem(unsigned long addr, unsigned long size, } #endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */ +static unsigned long align_idx(struct bootmem_data *bdata, unsigned long idx, + unsigned long step) +{ + unsigned long base = bdata->node_min_pfn; + + /* + * Align the index with respect to the node start so that the + * combination of both satisfies the requested alignment. + */ + + return ALIGN(base + idx, step) - base; +} + +static unsigned long align_off(struct bootmem_data *bdata, unsigned long off, + unsigned long align) +{ + unsigned long base = PFN_PHYS(bdata->node_min_pfn); + + /* Same as align_idx for byte offsets */ + + return ALIGN(base + off, align) - base; +} + static void * __init alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size, unsigned long align, unsigned long goal, unsigned long limit) @@ -441,7 +464,7 @@ static void * __init alloc_bootmem_core(struct bootmem_data *bdata, else start = ALIGN(min, step); - sidx = start - bdata->node_min_pfn;; + sidx = start - bdata->node_min_pfn; midx = max - bdata->node_min_pfn; if (bdata->hint_idx > sidx) { @@ -450,7 +473,7 @@ static void * __init alloc_bootmem_core(struct bootmem_data *bdata, * catch the fallback below. */ fallback = sidx + 1; - sidx = ALIGN(bdata->hint_idx, step); + sidx = align_idx(bdata, bdata->hint_idx, step); } while (1) { @@ -459,7 +482,7 @@ static void * __init alloc_bootmem_core(struct bootmem_data *bdata, unsigned long eidx, i, start_off, end_off; find_block: sidx = find_next_zero_bit(bdata->node_bootmem_map, midx, sidx); - sidx = ALIGN(sidx, step); + sidx = align_idx(bdata, sidx, step); eidx = sidx + PFN_UP(size); if (sidx >= midx || eidx > midx) @@ -467,7 +490,7 @@ find_block: for (i = sidx; i < eidx; i++) if (test_bit(i, bdata->node_bootmem_map)) { - sidx = ALIGN(i, step); + sidx = align_idx(bdata, i, step); if (sidx == i) sidx += step; goto find_block; @@ -475,7 +498,7 @@ find_block: if (bdata->last_end_off & (PAGE_SIZE - 1) && PFN_DOWN(bdata->last_end_off) + 1 == sidx) - start_off = ALIGN(bdata->last_end_off, align); + start_off = align_off(bdata, bdata->last_end_off, align); else start_off = PFN_PHYS(sidx); @@ -499,7 +522,7 @@ find_block: } if (fallback) { - sidx = ALIGN(fallback - 1, step); + sidx = align_idx(bdata, fallback - 1, step); fallback = 0; goto find_block; } -- 2.7.4