Messages in this thread | | | Date | Fri, 4 Nov 2005 02:41:51 +0530 | From | Dipankar Sarma <> | Subject | Re: bad page state under possibly oom situation |
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On Thu, Nov 03, 2005 at 07:38:09AM +0100, Manfred Spraul wrote: > Hugh Dickins wrote: > > >(I don't know that it makes any difference, but was this particular report > >from 2.6.9-rc2 or from 2.6.14 or from something else? In both 2.6.9 and > >2.6.14, flags 0x90 mean PG_slab|PG_dirty.) > > > A very odd combination: > - free_pages_check() ensures that neither PG_slab nor PG_dirty are set > - prep_new_page() complains that both PG_slab and PG_dirty are set > - AFAICS slab doesn't set PG_dirty, and noone except slab set PG_slab. > > I don't understand how two wrong bits can end up in page->flags. > Dipankar, could you modify bad_page() and hexdump +-128 bytes? Perhaps > someone overwrites random memory. Or change the value of PG_slab to 20 > and check if page->flags remains 0x90.
Here is a dump of the page struct when this happens (two different instances) -
/* Dump of struct page */ page = ffff810008005550 4000005500009090 ffffffffffffffff 0 0 0 100100 200200 4000000000000000 ffffffffffffffff 0 0 0 ffff8100080055e8 ffffffff805ba370 4000000000000000 ffffffffffffffff
Bad page state at prep_new_page (in process 'rename14', page ffff810008005550) flags:0x4000005500009090 mapping:0000000000000000 mapcount:0 count:0 Backtrace:
Call Trace:<ffffffff80150388>{bad_page+115} <ffffffff80150bf0>{buffered_rmqueue+501} <ffffffff8017e2da>{alloc_inode+18} <ffffffff80150de7>{__alloc_pages+251} <ffffffff801535f3>{cache_alloc_refill+581} <ffffffff8015388f>{kmem_cache_alloc+44} <ffffffff80169440>{get_empty_filp+71} <ffffffff801670af>{filp_open+49} <ffffffff80166e28>{get_unused_fd+98} <ffffffff8016713d>{do_sys_open+59} <ffffffff8010e636>{system_call+126} Trying to fix it up, but a reboot is needed page = ffff81000800aaa0 4000000000000000 ffffffff00900055 0 0 0 100100 200200 4000000000000000 ffffffffffffffff 0 0 0 ffff81000800ab38 ffffffff805ba370 4000000000000000 ffffffffffffffff Bad page state at prep_new_page (in process 'rename14', page ffff81000800aaa0) flags:0x4000000000000000 mapping:0000000000000000 mapcount:0 count:9437270 Backtrace:
Call Trace:<ffffffff80150388>{bad_page+115} <ffffffff80150bf0>{buffered_rmqueue+501} <ffffffff80150de7>{__alloc_pages+251} <ffffffff801535f3>{cache_alloc_refill+581} <ffffffff8015388f>{kmem_cache_alloc+44} <ffffffff8017cd95>{d_alloc+33} <ffffffff801750be>{__lookup_hash+206} <ffffffff8017677b>{open_namei+276} <ffffffff801670ce>{filp_open+80} <ffffffff80166e28>{get_unused_fd+98} <ffffffff8016713d>{do_sys_open+59} <ffffffff8010e636>{system_call+1
I had set PG_slab to 20, so it is not necessarily a corrupted slab page.
Thanks Dipankar - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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