Re: Kernel BUG at fs/mpage.c:489

From: Andrew Morton
Date: Wed Feb 13 2008 - 04:05:00 EST


On Wed, 13 Feb 2008 08:26:27 +0100 Bart Dopheide <dopheide@xxxxxx> wrote:

> On Wed, Feb 13, 2008 at 12:05:45PM +1100, Nick Piggin wrote:
> :)On Wednesday 13 February 2008 08:50, Alan Cox wrote:
> :)> Almost certainly a hardware fail of some sort.
> :)
> :)Right, but the kernel shouldn't go bug...
>
> Indeed, that's why I'm reporting.
>
>
> :)I don't have a copy of your exact source code... which condition in
> :)__mpage_writepage went BUG?
>
> BUG_ON(buffer_locked(bh));
>
> In a bit of context:
> 482: if (page_has_buffers(page)) {
> 483: struct buffer_head *head = page_buffers(page);
> 484: struct buffer_head *bh = head;
> 485:
> 486: /* If they're all mapped and dirty, do it */
> 487: page_block = 0;
> 488: do {
> 489: BUG_ON(buffer_locked(bh));
> 490: if (!buffer_mapped(bh)) {
> 491: /*
> 492: * unmapped dirty buffers are created by
> 493: * __set_page_dirty_buffers -> mmapped data
> 494: */
> 495: if (buffer_dirty(bh))
> 496: goto confused;
> 497: if (first_unmapped == blocks_per_page)
> 498: first_unmapped = page_block;
> 499: continue;
> 500: }
>

Probably means that either fat, IDE, block or fs/buffer.c failed to unlock a buffer_head
when the IO error happened. It's unlikely to be fat.

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