Re: X freezes kernel during exit [Re: 2.6.23-rc3-mm1]

[Jiri Slaby <jirislaby@gmail.com>]

On 09/09/2007 04:33 PM, Andi Kleen wrote:
> On Sun, Sep 09, 2007 at 04:26:22PM +0200, Jiri Slaby wrote:
>> BTW it is reproducible for me on two different machines (i386-x86_64,
>> radeon-intel), don't you have the problem too?
> 
> No problems here with a radeon, no.
> 
> Does your CPU have clflush or not in /proc/cpuinfo?

BTW this is how my flush_kernel_map looks like:

static void flush_kernel_map(void *arg)
{
        struct flush_arg *a = (struct flush_arg *)arg;
        struct page *pg;
        unsigned int xx = 0;

        /* When clflush is available use it because it is
           much cheaper than WBINVD. */
        printk("%s: 1\n", __func__);
        if (a->full_flush || !cpu_has_clflush)
                asm volatile("wbinvd" ::: "memory");
        else list_for_each_entry(pg, &a->l, lru) {
        printk("%s: %10u 1a\n", __func__, xx++);
                if (PageFlush(pg))
                        clflush_cache_range(page_address(pg), PAGE_SIZE);
        }
        printk("%s: 2\n", __func__);
        __flush_tlb_all();
        printk("%s: 3\n", __func__);
}

It outputs 1a in the infinite loop with incrementing xx. But only in this case,
some global_flush_tlb are OK. e.g.:
Sep 10 01:39:19 localhost kernel: agpgart: Detected an Intel G33 Chipset.
Sep 10 01:39:19 localhost kernel: global_flush_tlb: 1
Sep 10 01:39:19 localhost kernel: flush_kernel_map: 1
Sep 10 01:39:19 localhost kernel: flush_kernel_map:          0 1a
Sep 10 01:39:19 localhost kernel: flush_kernel_map:          1 1a
Sep 10 01:39:19 localhost kernel: flush_kernel_map: 2
Sep 10 01:39:19 localhost kernel: flush_kernel_map: 3
Sep 10 01:39:19 localhost kernel: flush_kernel_map: 1
Sep 10 01:39:19 localhost kernel: flush_kernel_map:          0 1a
Sep 10 01:39:19 localhost kernel: flush_kernel_map:          1 1a
Sep 10 01:39:19 localhost kernel: flush_kernel_map: 2
Sep 10 01:39:19 localhost kernel: flush_kernel_map: 3
Sep 10 01:39:19 localhost kernel: global_flush_tlb: 2
Sep 10 01:39:19 localhost kernel: global_flush_tlb: 3
Sep 10 01:39:19 localhost kernel: agpgart: Detected 6140K stolen memory.

It seems, that the list is broken only on X shutdown. How can be deferred-pages
list inited in some bad manner, when list_replace_init is called on it? Weird.

-- 
Jiri Slaby (jirislaby@gmail.com)
Faculty of Informatics, Masaryk University
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