Messages in this thread Patch in this message | | | Date | Tue, 19 Dec 2006 18:02:34 +1100 | From | Nick Piggin <> | Subject | Re: -mm merge plans for 2.6.20 |
| |
Dave Jones wrote: > On Tue, Dec 19, 2006 at 04:20:37PM +1100, Nick Piggin wrote: > > Dave Jones wrote: > > > > > Eeek! page_mapcount(page) went negative! (-2) > > > > Hmm, probably happened once before, too. > > You're right. Going back further in the log, I noticed > that it had happened again exactly at the time that cron restarted vpnc. > The first time, the flags were different.. > > Dec 4 00:01:03 firewall kernel: Eeek! page_mapcount(page) went negative! (-1) > Dec 4 00:01:03 firewall kernel: page->flags = 400 > Dec 4 00:01:03 firewall kernel: page->count = 1 > Dec 4 00:01:03 firewall kernel: page->mapping = 00000000
Still reserved, with a NULL mapping. I'd say it could be the same page.
> > > > page->flags = 404 > > > > What's that? PG_referenced|PG_reserved? So I'd say it is likely > > that some driver has got its refcounting wrong. > > At the time that it bit me, here's what was loaded.. > > tun ipt_MASQUERADE iptable_nat ip_nat ipt_LOG xt_limit ipv6 > ip_conntrack_netbios_ns ipt_REJECT xt_state ip_conntrack nfnetlink xt_tcpudp > iptable_filter ip_tables x_tables video sbs i2c_ec button battery asus_acpi ac > parport_pc lp parport pcspkr ide_cd i2c_viapro i2c_core cdrom 3c59x via_rhine > via_ircc mii irda crc_ccitt serio_raw dm_snapshot dm_zero dm_mirror dm_mod ext3 > jbd ehci_hcd ohci_hcd uhci_hcd > > The scary ones (i2c, irda) weren't in use at all, and had never been opened afaik, > so the potential for those to be corrupting memory is slim, but not out of the > question. (Why the hell asus_acpi is loaded is a mystery, this isn't an Asus, > or a laptop. Probably dumb initscripts).
OK that could be useful if I do some grepping and see which ones are setting PG_reserved.
> > And I see we've got another report for 2.6.19.1 from Chris, which > > is equally vague. > > I'll be moving that box to 2.6.19.x at some point real soon, so I'll holler > if I see it again on a later kernel. > > > IMO the pattern is much too consistent to be able to attribute > > them all to hardware problems. And considering it takes so long > > for these things to appear, can we get something like the attached > > patch upstream at least until we manage to stamp them out? > > Sounds like a good idea to me. > > ACKed-by: Dave Jones <davej@redhat.com>
Thanks.
> > > Any other debugging info we can add? > > Would it be useful to print the pfn of the page ? > In cases like mine, where it bit twice before it killed the box, it > might be interesting to see if its always the same page. Not sure > what that would prove/disprove though.
Might help. I guess the site where it is allocated from might be another one, although I'm hoping that if we know what ->nopage is being used then we'll be able to track it. OTOH it may be using remap_pfn_range from fops->mmap, rather than nopage... I wonder how we could get at that info? vma->vm_file->f_op->mmap?
-- SUSE Labs, Novell Inc. Index: linux-2.6/include/linux/rmap.h =================================================================== --- linux-2.6.orig/include/linux/rmap.h 2006-12-04 19:56:17.000000000 +1100 +++ linux-2.6/include/linux/rmap.h 2006-12-19 16:14:30.000000000 +1100 @@ -72,7 +72,7 @@ void __anon_vma_link(struct vm_area_stru void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); void page_add_file_rmap(struct page *); -void page_remove_rmap(struct page *); +void page_remove_rmap(struct page *, struct vm_area_struct *); /** * page_dup_rmap - duplicate pte mapping to a page Index: linux-2.6/mm/filemap_xip.c =================================================================== --- linux-2.6.orig/mm/filemap_xip.c 2006-12-04 19:07:10.000000000 +1100 +++ linux-2.6/mm/filemap_xip.c 2006-12-19 16:14:30.000000000 +1100 @@ -189,7 +189,7 @@ __xip_unmap (struct address_space * mapp /* Nuke the page table entry. */ flush_cache_page(vma, address, pte_pfn(*pte)); pteval = ptep_clear_flush(vma, address, pte); - page_remove_rmap(page); + page_remove_rmap(page, vma); dec_mm_counter(mm, file_rss); BUG_ON(pte_dirty(pteval)); pte_unmap_unlock(pte, ptl); Index: linux-2.6/mm/fremap.c =================================================================== --- linux-2.6.orig/mm/fremap.c 2006-12-04 19:56:20.000000000 +1100 +++ linux-2.6/mm/fremap.c 2006-12-19 16:14:30.000000000 +1100 @@ -33,7 +33,7 @@ static int zap_pte(struct mm_struct *mm, if (page) { if (pte_dirty(pte)) set_page_dirty(page); - page_remove_rmap(page); + page_remove_rmap(page, vma); page_cache_release(page); } } else { Index: linux-2.6/mm/memory.c =================================================================== --- linux-2.6.orig/mm/memory.c 2006-12-04 19:56:21.000000000 +1100 +++ linux-2.6/mm/memory.c 2006-12-19 16:14:30.000000000 +1100 @@ -681,7 +681,7 @@ static unsigned long zap_pte_range(struc mark_page_accessed(page); file_rss--; } - page_remove_rmap(page); + page_remove_rmap(page, vma); tlb_remove_page(tlb, page); continue; } @@ -1576,7 +1576,7 @@ gotten: page_table = pte_offset_map_lock(mm, pmd, address, &ptl); if (likely(pte_same(*page_table, orig_pte))) { if (old_page) { - page_remove_rmap(old_page); + page_remove_rmap(old_page, vma); if (!PageAnon(old_page)) { dec_mm_counter(mm, file_rss); inc_mm_counter(mm, anon_rss); Index: linux-2.6/mm/rmap.c =================================================================== --- linux-2.6.orig/mm/rmap.c 2006-12-04 19:56:21.000000000 +1100 +++ linux-2.6/mm/rmap.c 2006-12-19 18:02:18.000000000 +1100 @@ -47,6 +47,7 @@ #include <linux/rmap.h> #include <linux/rcupdate.h> #include <linux/module.h> +#include <linux/kallsyms.h> #include <asm/tlbflush.h> @@ -567,14 +568,20 @@ void page_add_file_rmap(struct page *pag * * The caller needs to hold the pte lock. */ -void page_remove_rmap(struct page *page) +void page_remove_rmap(struct page *page, struct vm_area_struct *vma) { if (atomic_add_negative(-1, &page->_mapcount)) { if (unlikely(page_mapcount(page) < 0)) { printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); + printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(page)); printk (KERN_EMERG " page->flags = %lx\n", page->flags); printk (KERN_EMERG " page->count = %x\n", page_count(page)); printk (KERN_EMERG " page->mapping = %p\n", page->mapping); + print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops); + if (vma->vm_ops) + print_symbol (KERN_EMERG " vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage); + if (vma->vm_file && vma->vm_file->f_op) + print_symbol (KERN_EMERG " vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap); BUG(); } @@ -679,7 +686,7 @@ static int try_to_unmap_one(struct page dec_mm_counter(mm, file_rss); - page_remove_rmap(page); + page_remove_rmap(page, vma); page_cache_release(page); out_unmap: @@ -769,7 +776,7 @@ static void try_to_unmap_cluster(unsigne if (pte_dirty(pteval)) set_page_dirty(page); - page_remove_rmap(page); + page_remove_rmap(page, vma); page_cache_release(page); dec_mm_counter(mm, file_rss); (*mapcount)--; | |