On Tue, Apr 19, 2011 at 23:29, James Bottomley
<James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote:
Slub makes assumptions about page_to_nid() which are violated by
DISCONTIGMEM and !NUMA. ÂThis violation results in a panic because
page_to_nid() can be non-zero for pages in the discontiguous ranges and
this leads to a null return by get_node(). ÂThe assertion by the
maintainer is that DISCONTIGMEM should only be allowed when NUMA is also
defined. ÂHowever, at least six architectures: alpha, ia64, m32r, m68k,
mips, parisc violate this. ÂThe panic is a regression against slab, so
just mark slub broken in the problem configuration to prevent users
reporting these panics.
How does the problem manifest itself? We're having a problem on m68k, which
seems to go away when switching from SLUB to SLAB, or when reverting a commit
in [2] (probably this was never reported upstream).
References:
[1] http://www.mail-archive.com/linux-m68k@xxxxxxxxxxxxxxx/msg02812.html
[2] http://www.spinics.net/lists/linux-m68k/msg03401.html
Cc: stable@xxxxxxxxxx
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxx>
---
diff --git a/init/Kconfig b/init/Kconfig
index 56240e7..a7ad8fb 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1226,6 +1226,7 @@ config SLAB
    Âper cpu and per node queues.
Âconfig SLUB
+ Â Â Â depends on BROKEN || NUMA || !DISCONTIGMEM
   Âbool "SLUB (Unqueued Allocator)"
   Âhelp
     SLUB is a slab allocator that minimizes cache line usage
Gr{oetje,eeting}s,
            Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
             Â Â -- Linus Torvalds
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