Hi, andrew morton: This patch has been acked by kosaki motohiro. Is it OK to be merged into -mm tree? Thanks Wen Congyang At 10/19/2012 02:46 PM, wency@xxxxxxxxxxxxxx Wrote: > From: Wen Congyang <wency@xxxxxxxxxxxxxx> > > If sparse memory vmemmap is enabled, we can't free the memory to store > struct page when a memory device is hotremoved, because we may store > struct page in the memory to manage the memory which doesn't belong > to this memory device. When we hotadded this memory device again, we > will reuse this memory to store struct page, and struct page may > contain some obsolete information, and we will get bad-page state: > > [ 59.611278] init_memory_mapping: [mem 0x80000000-0x9fffffff] > [ 59.637836] Built 2 zonelists in Node order, mobility grouping on. Total pages: 547617 > [ 59.638739] Policy zone: Normal > [ 59.650840] BUG: Bad page state in process bash pfn:9b6dc > [ 59.651124] page:ffffea0002200020 count:0 mapcount:0 mapping: (null) index:0xfdfdfdfdfdfdfdfd > [ 59.651494] page flags: 0x2fdfdfdfd5df9fd(locked|referenced|uptodate|dirty|lru|active|slab|owner_priv_1|private|private_2|writeback|head|tail|swapcache|reclaim|swapbacked|unevictable|uncached|compound_lock) > [ 59.653604] Modules linked in: netconsole acpiphp pci_hotplug acpi_memhotplug loop kvm_amd kvm microcode tpm_tis tpm tpm_bios evdev psmouse serio_raw i2c_piix4 i2c_core parport_pc parport processor button thermal_sys ext3 jbd mbcache sg sr_mod cdrom ata_generic virtio_net ata_piix virtio_blk libata virtio_pci virtio_ring virtio scsi_mod > [ 59.656998] Pid: 988, comm: bash Not tainted 3.6.0-rc7-guest #12 > [ 59.657172] Call Trace: > [ 59.657275] [<ffffffff810e9b30>] ? bad_page+0xb0/0x100 > [ 59.657434] [<ffffffff810ea4c3>] ? free_pages_prepare+0xb3/0x100 > [ 59.657610] [<ffffffff810ea668>] ? free_hot_cold_page+0x48/0x1a0 > [ 59.657787] [<ffffffff8112cc08>] ? online_pages_range+0x68/0xa0 > [ 59.657961] [<ffffffff8112cba0>] ? __online_page_increment_counters+0x10/0x10 > [ 59.658162] [<ffffffff81045561>] ? walk_system_ram_range+0x101/0x110 > [ 59.658346] [<ffffffff814c4f95>] ? online_pages+0x1a5/0x2b0 > [ 59.658515] [<ffffffff8135663d>] ? __memory_block_change_state+0x20d/0x270 > [ 59.658710] [<ffffffff81356756>] ? store_mem_state+0xb6/0xf0 > [ 59.658878] [<ffffffff8119e482>] ? sysfs_write_file+0xd2/0x160 > [ 59.659052] [<ffffffff8113769a>] ? vfs_write+0xaa/0x160 > [ 59.659212] [<ffffffff81137977>] ? sys_write+0x47/0x90 > [ 59.659371] [<ffffffff814e2f25>] ? async_page_fault+0x25/0x30 > [ 59.659543] [<ffffffff814ea239>] ? system_call_fastpath+0x16/0x1b > [ 59.659720] Disabling lock debugging due to kernel taint > > This patch clears the memory to store struct page to avoid unexpected error. > > CC: David Rientjes <rientjes@xxxxxxxxxx> > CC: Jiang Liu <liuj97@xxxxxxxxx> > Cc: Minchan Kim <minchan.kim@xxxxxxxxx> > CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > CC: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> > Reported-by: Vasilis Liaskovitis <vasilis.liaskovitis@xxxxxxxxxxxxxxxx> > Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx> > --- > mm/sparse.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index fac95f2..0021265 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -638,7 +638,6 @@ static struct page *__kmalloc_section_memmap(unsigned long nr_pages) > got_map_page: > ret = (struct page *)pfn_to_kaddr(page_to_pfn(page)); > got_map_ptr: > - memset(ret, 0, memmap_size); > > return ret; > } > @@ -760,6 +759,8 @@ int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn, > goto out; > } > > + memset(memmap, 0, sizeof(struct page) * nr_pages); > + > ms->section_mem_map |= SECTION_MARKED_PRESENT; > > ret = sparse_init_one_section(ms, section_nr, memmap, usemap); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>