From 298359c5bf06c04258d7cf552426e198c47e83c1 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 23 Mar 2010 13:35:37 -0700 Subject: exit: fix oops in sync_mm_rss In 2.6.34-rc1, removing vhost_net module causes an oops in sync_mm_rss (called from do_exit) when workqueue is destroyed. This does not happen on net-next, or with vhost on top of to 2.6.33. The issue seems to be introduced by 34e55232e59f7b19050267a05ff1226e5cd122a5 ("mm: avoid false sharing of mm_counter) which added sync_mm_rss() that is passed task->mm, and dereferences it without checking. If task is a kernel thread, mm might be NULL. I think this might also happen e.g. with aio. This patch fixes the oops by calling sync_mm_rss when task->mm is set to NULL. I also added BUG_ON to detect any other cases where counters get incremented while mm is NULL. The oops I observed looks like this: BUG: unable to handle kernel NULL pointer dereference at 00000000000002a8 IP: [] sync_mm_rss+0x33/0x6f PGD 0 Oops: 0002 [#1] SMP last sysfs file: /sys/devices/system/cpu/cpu7/cache/index2/shared_cpu_map CPU 2 Modules linked in: vhost_net(-) tun bridge stp sunrpc ipv6 cpufreq_ondemand acpi_cpufreq freq_table kvm_intel kvm i5000_edac edac_core rtc_cmos bnx2 button i2c_i801 i2c_core rtc_core e1000e sg joydev ide_cd_mod serio_raw pcspkr rtc_lib cdrom virtio_net virtio_blk virtio_pci virtio_ring virtio af_packet e1000 shpchp aacraid uhci_hcd ohci_hcd ehci_hcd [last unloaded: microcode] Pid: 2046, comm: vhost Not tainted 2.6.34-rc1-vhost #25 System Planar/IBM System x3550 -[7978B3G]- RIP: 0010:[] [] sync_mm_rss+0x33/0x6f RSP: 0018:ffff8802379b7e60 EFLAGS: 00010202 RAX: 0000000000000008 RBX: ffff88023f2390c0 RCX: 0000000000000000 RDX: ffff88023f2396b0 RSI: 0000000000000000 RDI: ffff88023f2390c0 RBP: ffff8802379b7e60 R08: 0000000000000000 R09: 0000000000000000 R10: ffff88023aecfbc0 R11: 0000000000013240 R12: 0000000000000000 R13: ffffffff81051a6c R14: ffffe8ffffc0f540 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff880001e80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000000002a8 CR3: 000000023af23000 CR4: 00000000000406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process vhost (pid: 2046, threadinfo ffff8802379b6000, task ffff88023f2390c0) Stack: ffff8802379b7ee0 ffffffff81040687 ffffe8ffffc0f558 ffffffffa00a3e2d <0> 0000000000000000 ffff88023f2390c0 ffffffff81055817 ffff8802379b7e98 <0> ffff8802379b7e98 0000000100000286 ffff8802379b7ee0 ffff88023ad47d78 Call Trace: [] do_exit+0x147/0x6c4 [] ? handle_rx_net+0x0/0x17 [vhost_net] [] ? autoremove_wake_function+0x0/0x39 [] ? worker_thread+0x0/0x229 [] kthreadd+0x0/0xf2 [] kernel_thread_helper+0x4/0x10 [] ? kthread+0x0/0x87 [] ? kernel_thread_helper+0x0/0x10 Code: 00 8b 87 6c 02 00 00 85 c0 74 14 48 98 f0 48 01 86 a0 02 00 00 c7 87 6c 02 00 00 00 00 00 00 8b 87 70 02 00 00 85 c0 74 14 48 98 48 01 86 a8 02 00 00 c7 87 70 02 00 00 00 00 00 00 8b 87 74 RIP [] sync_mm_rss+0x33/0x6f RSP CR2: 00000000000002a8 ---[ end trace 41603ba922beddd2 ]--- Fixing recursive fault but reboot is needed! (note: handle_rx_net is a work item using workqueue in question). sync_mm_rss+0x33/0x6f gave me a hint. I also tried reverting 34e55232e59f7b19050267a05ff1226e5cd122a5 and the oops goes away. The module in question calls use_mm and later unuse_mm from a kernel thread. It is when this kernel thread is destroyed that the crash happens. Signed-off-by: Michael S. Tsirkin Andrea Arcangeli Reviewed-by: Rik van Riel Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 1 + 1 file changed, 1 insertion(+) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index 5b7f2002e54b..bc9ba5a1f5b9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -130,6 +130,7 @@ void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm) for (i = 0; i < NR_MM_COUNTERS; i++) { if (task->rss_stat.count[i]) { + BUG_ON(!mm); add_mm_counter(mm, i, task->rss_stat.count[i]); task->rss_stat.count[i] = 0; } -- cgit v1.2.3 From 5a0e3ad6af8660be21ca98a971cd00f331318c05 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 24 Mar 2010 17:04:11 +0900 Subject: include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo Guess-its-ok-by: Christoph Lameter Cc: Ingo Molnar Cc: Lee Schermerhorn --- mm/memory.c | 1 + 1 file changed, 1 insertion(+) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index bc9ba5a1f5b9..1d2ea39260e5 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #include -- cgit v1.2.3 From a3a2e76c77fa22b114e421ac11dec0c56c3503fb Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Tue, 6 Apr 2010 14:34:42 -0700 Subject: mm: avoid null-pointer deref in sync_mm_rss() - We weren't zeroing p->rss_stat[] at fork() - Consequently sync_mm_rss() was dereferencing tsk->mm for kernel threads and was oopsing. - Make __sync_task_rss_stat() static, too. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=15648 [akpm@linux-foundation.org: remove the BUG_ON(!mm->rss)] Reported-by: Troels Liebe Bentsen Signed-off-by: KAMEZAWA Hiroyuki "Michael S. Tsirkin" Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index 1d2ea39260e5..833952d8b74d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -125,13 +125,12 @@ core_initcall(init_zero_pfn); #if defined(SPLIT_RSS_COUNTING) -void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm) +static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm) { int i; for (i = 0; i < NR_MM_COUNTERS; i++) { if (task->rss_stat.count[i]) { - BUG_ON(!mm); add_mm_counter(mm, i, task->rss_stat.count[i]); task->rss_stat.count[i] = 0; } -- cgit v1.2.3