linux-kernel - Re: Regression - locking (all from 2.6.28)

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Date:	Sun, 22 Mar 2009 05:45:05 +0100
From:	jan sonnek <ha2nny@...il.com>
To:	linux-kernel@...r.kernel.org
CC:	catalin.marinas@....com, linux-scsi@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: Regression - locking (all from 2.6.28)

I have tried applied some patch (view down) to -mm kernel
(last mmotm 26.29-rc8-mm1), but It was not
successfull. When I have disabled Acceleration
(Option "NoAccel" "true"), I was able to start X system,
but in my dmesg is still error messages (attachement)


Bug page:
http://bugzilla.kernel.org/show_bug.cgi?id=12619

 > On Mon, 2009-03-02 at 12:11 -0800, Andrew Morton wrote:
 > > > Mar  1 00:06:51 localhost kernel: [   74.008165] unreferenced 
object 0xf6c4daf0 (size 52):
 > > > Mar  1 00:06:51 localhost kernel: [   74.008170]   comm 
"swapper", pid 1, jiffies 4294893427
 > > > Mar  1 00:06:51 localhost kernel: [   74.008175]   backtrace:
 > > > Mar  1 00:06:51 localhost kernel: [   74.008179]     [<c018978c>] 
kmemleak_alloc+0x17e/0x28e
 > > > Mar  1 00:06:51 localhost kernel: [   74.008185]     [<c0186b86>] 
kmem_cache_alloc+0xdc/0xe7
 > > > Mar  1 00:06:51 localhost kernel: [   74.008190]     [<c01a53bd>] 
alloc_buffer_head+0x16/0x71
 > > > Mar  1 00:06:51 localhost kernel: [   74.008196]     [<c01a5b91>] 
alloc_page_buffers+0x23/0xad
 > > > Mar  1 00:06:51 localhost kernel: [   74.008200]     [<c01a5fd4>] 
__getblk+0x192/0x26b
 > > > Mar  1 00:06:51 localhost kernel: [   74.008205]     [<c01d91f4>] 
jread+0x105/0x1de
 > > > Mar  1 00:06:51 localhost kernel: [   74.008209]     [<c01d932b>] 
do_one_pass+0x5e/0x38c
 > > > Mar  1 00:06:51 localhost kernel: [   74.008213]     [<c01d96f8>] 
journal_recover+0x41/0x9d
 > > > Mar  1 00:06:51 localhost kernel: [   74.008218]     [<c01db8d4>] 
journal_load+0x47/0x7b
 > > > Mar  1 00:06:51 localhost kernel: [   74.008221]     [<c01d43d1>] 
ext3_fill_super+0xe9d/0x144c
 > > > Mar  1 00:06:51 localhost kernel: [   74.008225]     [<c018d721>] 
get_sb_bdev+0xfa/0x140
 > > > Mar  1 00:06:51 localhost kernel: [   74.008231]     [<c01d2070>] 
ext3_get_sb+0x18/0x1a
 > > > Mar  1 00:06:51 localhost kernel: [   74.008235]     [<c018c71f>] 
vfs_kern_mount+0x41/0x7c
 > > > Mar  1 00:06:51 localhost kernel: [   74.008241]     [<c018c7a8>] 
do_kern_mount+0x37/0xbe
 > > > Mar  1 00:06:51 localhost kernel: [   74.008247]     [<c019f0bf>] 
do_mount+0x5f7/0x630
 > > > Mar  1 00:06:51 localhost kernel: [   74.008253]     [<c019f167>] 
sys_mount+0x6f/0xac
 > > I suspect kmemleak has gone nuts here.
 >
 > It seems that the buffer_head structure allocated above is stored in
 > page->private. However, the page structures are no longer scanned in
 > newer versions of kmemleak. That's the hunk that was removed after
 > comments about the contiguity of a node's memory:
 >
 > +     /* mem_map scanning */
 > +     for_each_online_node(i) {
 > +             struct page *page, *end;
 > +
 > +             page = NODE_MEM_MAP(i);
 > +             end  = page + NODE_DATA(i)->node_spanned_pages;
 > +
 > +             scan_block(page, end, NULL);
 > +     }
 >
 > The alternative is to inform kmemleak about the page structures returned
 > from __alloc_pages_internal() but there would be problems with recursive
 > calls into kmemleak when it allocates its own data structures.
 >
 > I'll look at re-adding the hunk above, maybe with some extra checks like
 > pfn_valid().

Looking again at this, the node_mem_map is always contiguous and the
code above only scans the node_mem_map, not the memory represented by
the node (which may not be contiguous). So I think it is a valid code
sequence.

If the above gets too deep into the nodes structure, an alternative
would be:

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 09b6fd7..0f17e62 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3552,6 +3552,11 @@ static void __init_refok 
alloc_node_mem_map(struct pglist_data *pgdat)
  		map = alloc_remap(pgdat->node_id, size);
  		if (!map)
  			map = alloc_bootmem_node(pgdat, size);
+		/*
+		 * Inform kmemleak to scan the node_mem_map arrays as the page
+		 * structure may contain pointers to other objects.
+		 */
+		kmemleak_alloc(map, size, 1, GFP_ATOMIC);
  		pgdat->node_mem_map = map + (pgdat->node_start_pfn - start);
  	}
  #ifndef CONFIG_NEED_MULTIPLE_NODES
-- 


Many thanks,
Jan Sonnek



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