From d8adde17e5f858427504725218c56aef90e90fc7 Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Wed, 11 Jul 2012 14:01:52 -0700 Subject: memory hotplug: fix invalid memory access caused by stale kswapd pointer kswapd_stop() is called to destroy the kswapd work thread when all memory of a NUMA node has been offlined. But kswapd_stop() only terminates the work thread without resetting NODE_DATA(nid)->kswapd to NULL. The stale pointer will prevent kswapd_run() from creating a new work thread when adding memory to the memory-less NUMA node again. Eventually the stale pointer may cause invalid memory access. An example stack dump as below. It's reproduced with 2.6.32, but latest kernel has the same issue. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] exit_creds+0x12/0x78 PGD 0 Oops: 0000 [#1] SMP last sysfs file: /sys/devices/system/memory/memory391/state CPU 11 Modules linked in: cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq microcode fuse loop dm_mod tpm_tis rtc_cmos i2c_i801 rtc_core tpm serio_raw pcspkr sg tpm_bios igb i2c_core iTCO_wdt rtc_lib mptctl iTCO_vendor_support button dca bnx2 usbhid hid uhci_hcd ehci_hcd usbcore sd_mod crc_t10dif edd ext3 mbcache jbd fan ide_pci_generic ide_core ata_generic ata_piix libata thermal processor thermal_sys hwmon mptsas mptscsih mptbase scsi_transport_sas scsi_mod Pid: 7949, comm: sh Not tainted 2.6.32.12-qiuxishi-5-default #92 Tecal RH2285 RIP: 0010:exit_creds+0x12/0x78 RSP: 0018:ffff8806044f1d78 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff880604f22140 RCX: 0000000000019502 RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000 RBP: ffff880604f22150 R08: 0000000000000000 R09: ffffffff81a4dc10 R10: 00000000000032a0 R11: ffff880006202500 R12: 0000000000000000 R13: 0000000000c40000 R14: 0000000000008000 R15: 0000000000000001 FS: 00007fbc03d066f0(0000) GS:ffff8800282e0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000000 CR3: 000000060f029000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process sh (pid: 7949, threadinfo ffff8806044f0000, task ffff880603d7c600) Stack: ffff880604f22140 ffffffff8103aac5 ffff880604f22140 ffffffff8104d21e ffff880006202500 0000000000008000 0000000000c38000 ffffffff810bd5b1 0000000000000000 ffff880603d7c600 00000000ffffdd29 0000000000000003 Call Trace: __put_task_struct+0x5d/0x97 kthread_stop+0x50/0x58 offline_pages+0x324/0x3da memory_block_change_state+0x179/0x1db store_mem_state+0x9e/0xbb sysfs_write_file+0xd0/0x107 vfs_write+0xad/0x169 sys_write+0x45/0x6e system_call_fastpath+0x16/0x1b Code: ff 4d 00 0f 94 c0 84 c0 74 08 48 89 ef e8 1f fd ff ff 5b 5d 31 c0 41 5c c3 53 48 8b 87 20 06 00 00 48 89 fb 48 8b bf 18 06 00 00 <8b> 00 48 c7 83 18 06 00 00 00 00 00 00 f0 ff 0f 0f 94 c0 84 c0 RIP exit_creds+0x12/0x78 RSP CR2: 0000000000000000 [akpm@linux-foundation.org: add pglist_data.kswapd locking comments] Signed-off-by: Xishi Qiu Signed-off-by: Jiang Liu Acked-by: KAMEZAWA Hiroyuki Acked-by: KOSAKI Motohiro Acked-by: Mel Gorman Acked-by: David Rientjes Reviewed-by: Minchan Kim Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 2427706f78b..68c569fcbb6 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -694,7 +694,7 @@ typedef struct pglist_data { range, including holes */ int node_id; wait_queue_head_t kswapd_wait; - struct task_struct *kswapd; + struct task_struct *kswapd; /* Protected by lock_memory_hotplug() */ int kswapd_max_order; enum zone_type classzone_idx; } pg_data_t; -- cgit v1.2.3-18-g5258 From 99ab7b19440a72ebdf225f99b20f8ef40decee86 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 11 Jul 2012 14:02:53 -0700 Subject: mm: sparse: fix usemap allocation above node descriptor section After commit f5bf18fa22f8 ("bootmem/sparsemem: remove limit constraint in alloc_bootmem_section"), usemap allocations may easily be placed outside the optimal section that holds the node descriptor, even if there is space available in that section. This results in unnecessary hotplug dependencies that need to have the node unplugged before the section holding the usemap. The reason is that the bootmem allocator doesn't guarantee a linear search starting from the passed allocation goal but may start out at a much higher address absent an upper limit. Fix this by trying the allocation with the limit at the section end, then retry without if that fails. This keeps the fix from f5bf18fa22f8 of not panicking if the allocation does not fit in the section, but still makes sure to try to stay within the section at first. Signed-off-by: Yinghai Lu Signed-off-by: Johannes Weiner Cc: [3.3.x, 3.4.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/bootmem.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include') diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h index 324fe08ea3b..6d6795d46a7 100644 --- a/include/linux/bootmem.h +++ b/include/linux/bootmem.h @@ -91,6 +91,11 @@ extern void *__alloc_bootmem_node_nopanic(pg_data_t *pgdat, unsigned long size, unsigned long align, unsigned long goal); +void *___alloc_bootmem_node_nopanic(pg_data_t *pgdat, + unsigned long size, + unsigned long align, + unsigned long goal, + unsigned long limit); extern void *__alloc_bootmem_low(unsigned long size, unsigned long align, unsigned long goal); -- cgit v1.2.3-18-g5258 From 29f6738609e40227dabcc63bfb3b84b3726a75bd Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 11 Jul 2012 14:02:56 -0700 Subject: memblock: free allocated memblock_reserved_regions later memblock_free_reserved_regions() calls memblock_free(), but memblock_free() would double reserved.regions too, so we could free the old range for reserved.regions. Also tj said there is another bug which could be related to this. | I don't think we're saving any noticeable | amount by doing this "free - give it to page allocator - reserve | again" dancing. We should just allocate regions aligned to page | boundaries and free them later when memblock is no longer in use. in that case, when DEBUG_PAGEALLOC, will get panic: memblock_free: [0x0000102febc080-0x0000102febf080] memblock_free_reserved_regions+0x37/0x39 BUG: unable to handle kernel paging request at ffff88102febd948 IP: [] __next_free_mem_range+0x9b/0x155 PGD 4826063 PUD cf67a067 PMD cf7fa067 PTE 800000102febd160 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC CPU 0 Pid: 0, comm: swapper Not tainted 3.5.0-rc2-next-20120614-sasha #447 RIP: 0010:[] [] __next_free_mem_range+0x9b/0x155 See the discussion at https://lkml.org/lkml/2012/6/13/469 So try to allocate with PAGE_SIZE alignment and free it later. Reported-by: Sasha Levin Acked-by: Tejun Heo Cc: Benjamin Herrenschmidt Signed-off-by: Yinghai Lu Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memblock.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/memblock.h b/include/linux/memblock.h index a6bb1023514..19dc455b4f3 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -50,9 +50,7 @@ phys_addr_t memblock_find_in_range_node(phys_addr_t start, phys_addr_t end, phys_addr_t size, phys_addr_t align, int nid); phys_addr_t memblock_find_in_range(phys_addr_t start, phys_addr_t end, phys_addr_t size, phys_addr_t align); -int memblock_free_reserved_regions(void); -int memblock_reserve_reserved_regions(void); - +phys_addr_t get_allocated_memblock_reserved_regions_info(phys_addr_t *addr); void memblock_allow_resize(void); int memblock_add_node(phys_addr_t base, phys_addr_t size, int nid); int memblock_add(phys_addr_t base, phys_addr_t size); -- cgit v1.2.3-18-g5258