Commit-ID: c1a0bf347c40dd4b0a5bb10fdf4de76a1fbbbe8c
Gitweb: http://git.kernel.org/tip/c1a0bf347c40dd4b0a5bb10fdf4de76a1fbbbe8c
Author: Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate: Mon, 8 Feb 2016 09:57:34 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 8 Feb 2016 12:14:25 +0100
x86/mm/numa: Clean up numa_clear_kernel_node_hotplug()
So we fixed an overflow bug in numa_clear_kernel_node_hotplug():
2b54ab3c66d4 ("x86/mm/numa: Fix memory corruption on 32-bit NUMA kernels")
... and the bug was indirectly caused by poor coding style,
such as using start/end local variables unnecessarily, which
lost the physaddr_t type.
So make the code more readable and try to fully comment all
the thinking behind the logic.
No change in functionality.
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Brad Spengler <spender@xxxxxxxxxxxxxx>
Cc: Chen Tang <imtangchen@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: PaX Team <pageexec@xxxxxxxxxxx>
Cc: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: y14sg1 <y14sg1@xxxxxxxxxxx>
Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/mm/numa.c | 65 +++++++++++++++++++++++++++++++++++-------------------
1 file changed, 42 insertions(+), 23 deletions(-)
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index d04f809..ede4506 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -465,46 +465,65 @@ static bool __init numa_meminfo_cover_memory(const struct numa_meminfo *mi)
return true;
}
+/*
+ * Mark all currently memblock-reserved physical memory (which covers the
+ * kernel's own memory ranges) as hot-unswappable.
+ */
static void __init numa_clear_kernel_node_hotplug(void)
{
- int i, nid;
- nodemask_t numa_kernel_nodes = NODE_MASK_NONE;
- phys_addr_t start, end;
- struct memblock_region *r;
+ nodemask_t reserved_nodemask = NODE_MASK_NONE;
+ struct memblock_region *mb_region;
+ int i;
/*
+ * We have to do some preprocessing of memblock regions, to
+ * make them suitable for reservation.
+ *
* At this time, all memory regions reserved by memblock are
- * used by the kernel. Set the nid in memblock.reserved will
- * mark out all the nodes the kernel resides in.
+ * used by the kernel, but those regions are not split up
+ * along node boundaries yet, and don't necessarily have their
+ * node ID set yet either.
+ *
+ * So iterate over all memory known to the x86 architecture,
+ * and use those ranges to set the nid in memblock.reserved.
+ * This will split up the memblock regions along node
+ * boundaries and will set the node IDs as well.
*/
for (i = 0; i < numa_meminfo.nr_blks; i++) {
- struct numa_memblk *mb = &numa_meminfo.blk[i];
+ struct numa_memblk *mb = numa_meminfo.blk + i;
- memblock_set_node(mb->start, mb->end - mb->start,
- &memblock.reserved, mb->nid);
+ memblock_set_node(mb->start, mb->end - mb->start, &memblock.reserved, mb->nid);
}
/*
- * Mark all kernel nodes.
+ * Now go over all reserved memblock regions, to construct a
+ * node mask of all kernel reserved memory areas.
*
- * When booting with mem=nn[kMG] or in a kdump kernel, numa_meminfo
- * may not include all the memblock.reserved memory ranges because
- * trim_snb_memory() reserves specific pages for Sandy Bridge graphics.
+ * [ Note, when booting with mem=nn[kMG] or in a kdump kernel,
+ * numa_meminfo might not include all memblock.reserved
+ * memory ranges, because quirks such as trim_snb_memory()
+ * reserve specific pages for Sandy Bridge graphics. ]
*/
- for_each_memblock(reserved, r)
- if (r->nid != MAX_NUMNODES)
- node_set(r->nid, numa_kernel_nodes);
+ for_each_memblock(reserved, mb_region) {
+ if (mb_region->nid != MAX_NUMNODES)
+ node_set(mb_region->nid, reserved_nodemask);
+ }
- /* Clear MEMBLOCK_HOTPLUG flag for memory in kernel nodes. */
+ /*
+ * Finally, clear the MEMBLOCK_HOTPLUG flag for all memory
+ * belonging to the reserved node mask.
+ *
+ * Note that this will include memory regions that reside
+ * on nodes that contain kernel memory - entire nodes
+ * become hot-unpluggable:
+ */
for (i = 0; i < numa_meminfo.nr_blks; i++) {
- nid = numa_meminfo.blk[i].nid;
- if (!node_isset(nid, numa_kernel_nodes))
- continue;
+ struct numa_memblk *mb = numa_meminfo.blk + i;
- start = numa_meminfo.blk[i].start;
- end = numa_meminfo.blk[i].end;
+ if (!node_isset(mb->nid, reserved_nodemask))
+ continue;
- memblock_clear_hotplug(start, end - start);
+ memblock_clear_hotplug(mb->start, mb->end - mb->start);
}
}
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|