Re: Warning on memory offline (and possible in usual migration?)

[Nick Piggin <npiggin@suse.de>]

On Mon, Apr 14, 2008 at 02:58:06PM +0900, KAMEZAWA Hiroyuki wrote:
> In 2.6.25-rc8-mm2.
> 
> I saw below warning at memory offlining. please help.
> (ia64/NUMA box with ext3 file system. Almost all memory are free memory.)
> ==
> 
> localhost.localdomain login: ------------[ cut here ]------------
> WARNING: at fs/buffer.c:720 __set_page_dirty+0x330/0x360()
> Modules linked in: ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge ipv6 ipmi_watchdog mptctl ipmi_devintf ipmi_si ipmi_msghandler vfat fat dm_multipath parport_pc lp parport sg tg3 e100 mii button shpchp dm_snapshot dm_zero dm_mirror dm_log dm_mod usb_storage mptspi mptscsih scsi_transport_spi mptbase sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci_hcd [last unloaded: ipmi_watchdog]
> 
> Call Trace:
>  [<a000000100015220>] show_stack+0x80/0xa0
>                                 sp=e000012027b9fae0 bsp=e000012027b99398
>  [<a000000100015270>] dump_stack+0x30/0x60
>                                 sp=e000012027b9fcb0 bsp=e000012027b99380
>  [<a000000100089ed0>] warn_on_slowpath+0x90/0xe0
>                                 sp=e000012027b9fcb0 bsp=e000012027b99358
>  [<a0000001001f8b10>] __set_page_dirty+0x330/0x360
>                                 sp=e000012027b9fda0 bsp=e000012027b99328
>  [<a0000001001ffb90>] __set_page_dirty_buffers+0xd0/0x280
>                                 sp=e000012027b9fda0 bsp=e000012027b992f8
>  [<a00000010012fec0>] set_page_dirty+0xc0/0x260
>                                 sp=e000012027b9fda0 bsp=e000012027b992d0
>  [<a000000100195670>] migrate_page_copy+0x5d0/0x5e0
>                                 sp=e000012027b9fda0 bsp=e000012027b992a8
>  [<a000000100197840>] buffer_migrate_page+0x2e0/0x3c0
>                                 sp=e000012027b9fda0 bsp=e000012027b99260
>  [<a000000100195eb0>] migrate_pages+0x770/0xe00
>                                 sp=e000012027b9fda0 bsp=e000012027b991a8
>  [<a000000100191250>] offline_pages+0x6f0/0xa20
>                                 sp=e000012027b9fdf0 bsp=e000012027b99118
>  [<a00000010006b1f0>] remove_memory+0x30/0x60
>                                 sp=e000012027b9fe20 bsp=e000012027b990f0
>  [<a000000100482c50>] memory_block_change_state+0x390/0x400
>                                 sp=e000012027b9fe20 bsp=e000012027b990a0
>  [<a000000100483720>] store_mem_state+0x1e0/0x200
>                                 sp=e000012027b9fe20 bsp=e000012027b99068
>  [<a0000001004718a0>] sysdev_store+0x60/0xa0
>                                 sp=e000012027b9fe20 bsp=e000012027b99030
>  [<a000000100246100>] sysfs_write_file+0x220/0x300
>                                 sp=e000012027b9fe20 bsp=e000012027b98fd0
>  [<a00000010019e2e0>] vfs_write+0x1a0/0x320
>                                 sp=e000012027b9fe20 bsp=e000012027b98f80
>  [<a00000010019edf0>] sys_write+0x70/0xe0
>                                 sp=e000012027b9fe20 bsp=e000012027b98f08
>  [<a00000010000a570>] ia64_trace_syscall+0xd0/0x110
>                                 sp=e000012027b9fe30 bsp=e000012027b98f08
>  [<a000000000010720>] __start_ivt_text+0xffffffff00010720/0x400
>                                 sp=e000012027ba0000 bsp=e000012027b98f08
> ==
> 
> This comes from fs/buffer.c
> ==
> static int __set_page_dirty(struct page *page,
>                 struct address_space *mapping, int warn)
> {
>         if (unlikely(!mapping))
>                 return !TestSetPageDirty(page);
> 
>         if (TestSetPageDirty(page))
>                 return 0;
> 
>         write_lock_irq(&mapping->tree_lock);
>         if (page->mapping) {    /* Race with truncate? */
>                 WARN_ON_ONCE(warn && !PageUptodate(page)); ---------(*)
> 
>                 if (mapping_cap_account_dirty(mapping)) {
>                         __inc_zone_page_state(page, NR_FILE_DIRTY);
>                         __inc_bdi_stat(mapping->backing_dev_info,
>                                         BDI_RECLAIMABLE);
>                         task_io_account_write(PAGE_CACHE_SIZE);
>                 }
>                 radix_tree_tag_set(&mapping->page_tree,
>                                 page_index(page), PAGECACHE_TAG_DIRTY);
>         }
>         write_unlock_irq(&mapping->tree_lock);
>         __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
> 
>         return 1;
> }
> ==
> Then, "page" is not Uptodate when it reaches (*).
> 
> But, migrate_page() call path is
> ==
>    buffer_migrate_page()
> 	-> lock all buffers on old pages.
> 	-> move buffers to newpage.
> 	-> migrate_page_copy(page, newpage)
> 		-> set_page_dirty().
> 	-> unlock all buffers().
> ==
> static void migrate_page_copy(struct page *newpage, struct page *page)
> {
>         copy_highpage(newpage, page);
> <snip>
>         if (PageUptodate(page))
>                 SetPageUptodate(newpage);
> <snip>
>         if (PageDirty(page)) {
>                 clear_page_dirty_for_io(page);
>                 set_page_dirty(newpage);------------------------(**)
>         }

As far as I can see, migration just wants to transfer the PG_dirty state
to newpage, not actually "mark newpage as entirely dirty". So this should
be something like redirty_page_for_writepage here (without the wbc part,
__set_page_dirty_nobuffers should be sufficient as we are mm/ and
presumably know what we're doing).


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>