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    SubjectRe: [git pull] m68k SLUB fix for 2.6.39
    On Thu, Apr 28, 2011 at 23:41, David Rientjes <> wrote:
    > On Thu, 28 Apr 2011, James Bottomley wrote:
    >> > Since 4a5fa3590f09 ([PARISC] slub: fix panic with DISCONTIGMEM) from
    >> > 2.6.39-rc4, you can't actually select slub on m68k without CONFIG_ADVANCED
    >> > and CONFIG_SINGLE_MEMORY_CHUNK because it otherwises defaults to
    >> > discontigmem.
    >> >
    >> > James tested hppa64 with my N_NORMAL_MEMORY fix and found that it turned
    >> > an SMP box into UP.  If you've tested slub on m68k without regressions,
    >> > then perhaps you'd like to add a "|| M68K" to CONFIG_SLUB?
    >> To be honest, I really don't see that fixing it.  As soon as you
    >> allocate memory beyond range zero, you move onto a non-zero node as far
    >> as slub is concerned, and that will oops.
    > Possible nodes are represented in slub with N_NORMAL_MEMORY, so the
    > kmem_cache_node structures are allocated and initialized based on this
    > nodemask.  As long as the memory ranges map to nodes set in the nodemask,
    > this should be fine.
    >> I think what the N_NORMAL_MEMORY patch did is just make it take a whiile
    >> before you start allocating from that range.  Try executing a memory
    >> balloon on the platform; that was how we first demonstrated the problem
    >> on parisc.
    > With parisc, you encountered an oops in add_partial() because the
    > kmem_cache_node structure for the memory range returned by page_to_nid()
    > was not allocated.  init_kmem_cache_nodes() takes care of this for all
    > memory ranges set in N_NORMAL_MEMORY.
    > Adding Christoph and Pekka to the cc if there is additional concerns about
    > slub on this architecture.

    My ARAnyM instance has

    System Memory: 276480K
    14 MB at 0x00000000 (ST-RAM)
    256 MB at 0x01000000 (alternate RAM)

    and 137800KIB of swap, and survived the following program just fine:

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>

    int main(int argc, char *argv[])
    size_t size = 1048576;
    size_t total = 0;
    void *p;

    while (size) {
    p = malloc(size);
    if (!p) {
    printf("Failed to allocate %zu bytes\n", size);
    size /= 2;
    memset(p, 0xaa, size);
    total += size;
    printf("Using %zu / 0x%zx bytes of memory\n", total, total);

    return 0;

    i.e. the OOM-killer just killed the program after it consumed all
    available virtual

    Out of memory: Kill process 1727 (malloctest) score 854 or sacrifice child
    Killed process 1727 (malloctest) total-vm:361160kB, anon-rss:224164kB,
    malloctest: page allocation failure. order:0, mode:0x84d0

    So SLUB really seems to work now.



    Geert Uytterhoeven -- There's lots of Linux beyond ia32 --

    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.
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