Messages in this thread Patch in this message | | | Date | Thu, 12 Jul 2007 22:18:42 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Add nid sanity on alloc_pages_node |
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On Fri, 13 Jul 2007 10:45:07 +0800 Joe Jin <joe.jin@oracle.com> wrote:
> This patch add nid sanity check on alloc_pages_node(). > While two process change nr_hugepages at a system, alloc_fresh_huge_page() > been called, at this function, nid defined as a static variable, but, there > is not any protection of, if 2 process called at the same time, maybe pass a > invalid nid to alloc_pages_node. > > We have hit it by following scripts: > > #!/bin/bash > while : ; do > echo 1000000000000 > /proc/sys/vm/nr_hugepages > echo 1 > /proc/sys/vm/nr_hugepages > echo 10000000000000000000 > /proc/sys/vm/nr_hugepages > echo 0 > /proc/sys/vm/nr_hugepages > done > > > Run the script at _two_ difference terminal, after a short time, a kernel panic > info will print. > > > Signed-off-by: Joe Jin <joe.jin@oracle.com> > --- > > --- linux-2.6.22/include/linux/gfp.h.orig 2007-07-12 15:06:23.000000000 +0800 > +++ linux-2.6.22/include/linux/gfp.h 2007-07-12 15:02:59.000000000 +0800 > @@ -133,6 +133,9 @@ > /* Unknown node is current node */ > if (nid < 0) > nid = numa_node_id(); > + > + if (unlikely(nid == MAX_NUMNODES)) > + nid = first_node(node_online_map); > > return __alloc_pages(gfp_mask, order, > NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_mask));
alloc_pages_node() is pretty much the last place where we want to fix this: it adds more cycles and more code to many important codepaths in the kernel.
It'd be much better to fix the race within alloc_fresh_huge_page(). That function is pretty pathetic.
Something like this?
--- a/mm/hugetlb.c~a +++ a/mm/hugetlb.c @@ -105,13 +105,20 @@ static void free_huge_page(struct page * static int alloc_fresh_huge_page(void) { - static int nid = 0; + static int prev_nid; + static DEFINE_SPINLOCK(nid_lock); struct page *page; - page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN, - HUGETLB_PAGE_ORDER); - nid = next_node(nid, node_online_map); + int nid; + + spin_lock(&nid_lock); + nid = next_node(prev_nid, node_online_map); if (nid == MAX_NUMNODES) nid = first_node(node_online_map); + prev_nid = nid; + spin_unlock(&nid_lock); + + page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN, + HUGETLB_PAGE_ORDER); if (page) { set_compound_page_dtor(page, free_huge_page); spin_lock(&hugetlb_lock); _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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