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    Subject[PATCH 4/4] kcore: remove noise from walk_memory_resource
    From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

    Originally, walk_memory_resource() was introduced to traverse all memory
    of "System RAM" for detecting memory hotplug/unplug range.
    For doing so, flags of IORESOUCE_MEM|IORESOURCE_BUSY was used and this
    was enough for memory hotplug because scanning range was controlled properly.

    But for using other purpose, /proc/kcore, this may includes some firmware
    area marked as IORESOURCE_BUSY | IORESOUCE_MEM. This patch makes the check
    strict to find out busy "System RAM".

    Note: PPC64 keeps their own walk_memory_resouce(), which walk through
    ppc64's lmb informaton. Because old kclist_add() is called per lmb,
    this patch makes no difference in behavior, finally.

    Changelog v2:
    - new patch from v2.

    Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    ---
    kernel/resource.c | 18 ++++++++++++++----
    1 file changed, 14 insertions(+), 4 deletions(-)

    Index: mmotm-2.6.31-Jul16/kernel/resource.c
    ===================================================================
    --- mmotm-2.6.31-Jul16.orig/kernel/resource.c
    +++ mmotm-2.6.31-Jul16/kernel/resource.c
    @@ -237,10 +237,10 @@ EXPORT_SYMBOL(release_resource);
    #if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
    /*
    * Finds the lowest memory reosurce exists within [res->start.res->end)
    - * the caller must specify res->start, res->end, res->flags.
    + * the caller must specify res->start, res->end, res->flags and "name".
    * If found, returns 0, res is overwritten, if not found, returns -1.
    */
    -static int find_next_system_ram(struct resource *res)
    +static int find_next_system_ram(struct resource *res, char *name)
    {
    resource_size_t start, end;
    struct resource *p;
    @@ -256,6 +256,8 @@ static int find_next_system_ram(struct r
    /* system ram is just marked as IORESOURCE_MEM */
    if (p->flags != res->flags)
    continue;
    + if (name && strcmp(p->name, name))
    + continue;
    if (p->start > end) {
    p = NULL;
    break;
    @@ -273,19 +275,27 @@ static int find_next_system_ram(struct r
    res->end = p->end;
    return 0;
    }
    +
    +/*
    + * This function calls callback against all memory range of "System RAM"
    + * which are marked as IORESOURCE_MEM and IORESOUCE_BUSY.
    + * Now, this function is only for "System RAM".
    + */
    int
    walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg,
    - int (*func)(unsigned long, unsigned long, void *))
    + int (*func)(unsigned long, unsigned long, void *))
    {
    struct resource res;
    unsigned long pfn, len;
    u64 orig_end;
    int ret = -1;
    +
    res.start = (u64) start_pfn << PAGE_SHIFT;
    res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
    res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
    orig_end = res.end;
    - while ((res.start < res.end) && (find_next_system_ram(&res) >= 0)) {
    + while ((res.start < res.end) &&
    + (find_next_system_ram(&res, "System RAM") >= 0)) {
    pfn = (unsigned long)(res.start >> PAGE_SHIFT);
    len = (unsigned long)((res.end + 1 - res.start) >> PAGE_SHIFT);
    ret = (*func)(pfn, len, arg);


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