Dump Page Cache state for out of memory

Hi,

I'm using the following code in order to
dump the state concerning the Page Cache
related to filesystem I/O, from out_of_memory().

Steffen

--

oo_kill.c:

...
typedef struct {
    unsigned long locked;    /* number locked pages */
    unsigned long clean;     /* number clean pages */
    unsigned long dirty;     /* number dirty pages */
    struct super_block *sb;  /* related superblock */
} dump_page_cache_entry_t;

static dump_page_cache_entry_t dump_page_cache_arr[16];

static dump_page_cache_entry_t *
get_dump_cache_entry (struct super_block *sb)
{
    int i;

    for(i=0; i < 16; i++){
        if(dump_page_cache_arr[i].sb == sb)  return &dump_page_cache_arr[i];
        if(dump_page_cache_arr[i].sb == NULL){
            dump_page_cache_arr[i].sb = sb;
            return &dump_page_cache_arr[i];
        }
    }
    return &dump_page_cache_arr[15];
}

/*  dump page cache state
 */

static void dump_page_cache (void)
{
    int i;
    struct page **p = page_hash_table;
    struct page  *q;
    unsigned long flags;
    unsigned long total  = 0;
    dump_page_cache_entry_t *ep;
    struct super_block *sb;

    for(i=0; i<PAGE_HASH_SIZE; i++){

        for(q=*p;q;q=q->next_hash){

            total++;
            if(q->mapping  && q->mapping->host && (sb=q->mapping->host->i_sb)){

                flags = q->flags;
                ep = get_dump_cache_entry(sb);

                if((flags & (1 << PG_locked))){
                    ep->locked++;
                }else{
                    if((flags & (1 << PG_dirty))){
                        if(flags & (1 << PG_uptodate)){
                            ep->dirty++;
                        }
                    }else{
                        ep->clean++;
                    }
                }
            }
        }
        p++;
    }

    printk(KERN_EMERG "%s (%d) %s(): Page Cache Status:\n", __FILE__, __LINE__, __func__);
    for(i=0; i<16; i++){

        dump_page_cache_entry_t *ce = &dump_page_cache_arr[i];

        if(ce->sb){

            printk(KERN_EMERG "%14s  clean: %-10d  locked: %-10d  dirty: %d\n",
                    ce->sb->s_type ? ce->sb->s_type->name : "???",
                    ce->clean, ce->locked, ce->dirty);
        }else{
            break;
        }
    }
    printk("%14s %d\n", "total", total);
}

...

void out_of_memory(void)
{
   ...
   dump_page_cache();
   ...
}