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H A D | vmalloc.c | diff d4033afdf8282802ad28b0ed854393454115a071 Mon Apr 29 17:07:35 CDT 2013 Joonsoo Kim <js1304@gmail.com> mm, vmalloc: iterate vmap_area_list, instead of vmlist, in vmallocinfo()
This patch is a preparatory step for removing vmlist entirely. For above purpose, we change iterating a vmap_list codes to iterating a vmap_area_list. It is somewhat trivial change, but just one thing should be noticed.
Using vmap_area_list in vmallocinfo() introduce ordering problem in SMP system. In s_show(), we retrieve some values from vm_struct. vm_struct's values is not fully setup when va->vm is assigned. Full setup is notified by removing VM_UNLIST flag without holding a lock. When we see that VM_UNLIST is removed, it is not ensured that vm_struct has proper values in view of other CPUs. So we need smp_[rw]mb for ensuring that proper values is assigned when we see that VM_UNLIST is removed.
Therefore, this patch not only change a iteration list, but also add a appropriate smp_[rw]mb to right places.
Signed-off-by: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Dave Anderson <anderson@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Ingo Molnar <mingo@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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