Messages in this thread Patch in this message | | | Date | Fri, 16 Oct 2009 15:32:59 +0200 | Subject | Re: Leaks in trace reported by kmemleak | From | Zdenek Kabelac <> |
| |
2009/10/16 Catalin Marinas <catalin.marinas@arm.com>: > On Fri, 2009-10-16 at 09:45 +0200, Zdenek Kabelac wrote: >> 2009/10/15 Catalin Marinas <catalin.marinas@arm.com>: >> >> Zdenek Kabelac wrote: >> >> > I've noticed your latest patch for memory leak in filter setting >> >> > (8ad807318fcd...) - but even with this patch - kmemleak seems to still >> >> > report lots (~900) of following leaks - note - they come only from >> >> > i915 and kvm module - so I'm not sure if these two modules are doing >> >> > something wrong or the problem is in trace code. >> > >> > It is probably caused by the fact that kmemleak doesn't scan the >> > mod->trace_events data in a module (the _ftrace_events section). It only >> > scans those sections beginning with .data and .bss in a module. Maybe we >> > should add "_ftrace_events" as well or just prefix it with ".data". >> > >> > Something like below may fix this (untested): >> > >> > diff --git a/kernel/module.c b/kernel/module.c >> > index 8b7d880..1449691 100644 >> > --- a/kernel/module.c >> > +++ b/kernel/module.c >> > @@ -2383,6 +2383,9 @@ static noinline struct module *load_module(void __user *umod, >> > "_ftrace_events", >> > sizeof(*mod->trace_events), >> > &mod->num_trace_events); >> > + kmemleak_scan_area(mod->module_core, mod->trace_events, >> > + sizeof(*mod->trace_events) * mod->num_trace_events, >> > + GFP_KERNEL); >> > #endif >> > #ifdef CONFIG_FTRACE_MCOUNT_RECORD >> > /* sechdrs[0].sh_size is always zero */ >> >> Yep - I've assume it could be also a problem of missing memory segment >> in kmemleak scanning routine - but it was weird that just these two >> modules (i915 & kvm) are doing such strange thing. >> >> I've tested patch above with added cast ( (unsigned >> long)mod->trace_events) to pacify warning - but it did not helped - >> leaks are still printed. > > Same trace-related leaks? >
Yes -same - though I forget to mention that log contained these two extra messages: (got lost in other debug stuff :( )...
So it could be the parameters in your first patch were not correct ?
[drm] Initialized drm 1.1.0 20060810 kmemleak: Scan area larger than object 0xffffffffa033b000 Pid: 1083, comm: modprobe Not tainted 2.6.32-rc5-00002-ga8ed0d4 #25 Call Trace: [<ffffffff8140ee5f>] kmemleak_scan_area+0x15f/0x1a0 [<ffffffff810a0086>] load_module+0xff6/0x1ae0 [<ffffffff8109ca70>] ? setup_modinfo_srcversion+0x0/0x30 [<ffffffff810a0beb>] sys_init_module+0x7b/0x260 [<ffffffff8100c11b>] system_call_fastpath+0x16/0x1b kmemleak: Object 0xffffffffa033b000 (size 307200): kmemleak: comm "modprobe", pid 1083, jiffies 4294881856 kmemleak: min_count = 0 kmemleak: count = -1 kmemleak: flags = 0x9 kmemleak: backtrace: [<ffffffff8140eae6>] kmemleak_alloc+0x26/0x60 [<ffffffff8111992a>] __vmalloc_area+0x4a/0x60 [<ffffffff8102b6ee>] module_alloc+0x5e/0x60 [<ffffffff8109c626>] module_alloc_update_bounds+0x16/0x50 [<ffffffff8109f8d3>] load_module+0x843/0x1ae0 [<ffffffff810a0beb>] sys_init_module+0x7b/0x260 [<ffffffff8100c11b>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff pci 0000:00:02.0: power state changed by ACPI to D0 pci 0000:00:02.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 acpi device:01: registered as cooling_device2 input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input8 ACPI: Video Device [VID] (multi-head: yes rom: no post: no) [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on minor 0 kmemleak: Scan area larger than object 0xffffffffa0399000 Pid: 1090, comm: modprobe Not tainted 2.6.32-rc5-00002-ga8ed0d4 #25 Call Trace: [<ffffffff8140ee5f>] kmemleak_scan_area+0x15f/0x1a0 [<ffffffff810a0086>] load_module+0xff6/0x1ae0 [<ffffffff8109ca70>] ? setup_modinfo_srcversion+0x0/0x30 [<ffffffff810a0beb>] sys_init_module+0x7b/0x260 [<ffffffff8100c11b>] system_call_fastpath+0x16/0x1b kmemleak: Object 0xffffffffa0399000 (size 278528): kmemleak: comm "modprobe", pid 1090, jiffies 4294881947 kmemleak: min_count = 0 kmemleak: count = -1 kmemleak: flags = 0x9 kmemleak: backtrace: [<ffffffff8140eae6>] kmemleak_alloc+0x26/0x60 [<ffffffff8111992a>] __vmalloc_area+0x4a/0x60 [<ffffffff8102b6ee>] module_alloc+0x5e/0x60 [<ffffffff8109c626>] module_alloc_update_bounds+0x16/0x50 [<ffffffff8109f8d3>] load_module+0x843/0x1ae0 [<ffffffff810a0beb>] sys_init_module+0x7b/0x260 [<ffffffff8100c11b>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff
> Do any of the leaks disappear with subsequent memory scans (echo scan > > debug/kmemleak)? >
Yep - they are persistent until module unload - for i915 though there are some left.
BTW - it's kind of ugly - that module removal destroys stack trace - it would be nice to see some hook for module unload - to eventually create a permanent stack trace for this occasion?? Otherwise when i915 is unloaded - I get leaks with unresolved addresses. (as a workaround I store leaks before unload and do a manual compare)
> Could you try the patch below? It ensures that all the module memory is > scanned: > > diff --git a/kernel/module.c b/kernel/module.c > index 8b7d880..fc6ef3a 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -2036,36 +2036,6 @@ static void *module_alloc_update_bounds(unsigned long size) > return ret; > } > > -#ifdef CONFIG_DEBUG_KMEMLEAK > -static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr, > - Elf_Shdr *sechdrs, char *secstrings) > -{
I'll check with next reboot.
>> And I add another leak - which might be from the same range of problem : >> (it's also present many times - and it even looks like hex dump is >> changing so it's probably even frequently used memory region - at >> least in few such objects) >> >> unreferenced object 0xffff88013aa4ad80 (size 192): >> comm "swapper", pid 1, jiffies 4294877809 >> hex dump (first 32 bytes): >> c0 dc a4 3a 01 88 ff ff 00 0c 79 39 01 88 ff ff ...:......y9.... >> 90 00 cf 3a 01 88 ff ff 02 00 00 00 00 00 00 00 ...:............ >> backtrace: >> [<ffffffff8140e9a6>] kmemleak_alloc+0x26/0x60 >> [<ffffffff81126a01>] kmem_cache_alloc_notrace+0xc1/0x140 >> [<ffffffff8127256a>] dma_debug_init+0x23a/0x3a0 >> [<ffffffff81864a37>] pci_iommu_init+0xe/0x28 >> [<ffffffff8100904c>] do_one_initcall+0x3c/0x1d0 >> [<ffffffff8185f4e6>] kernel_init+0x150/0x1a6 >> [<ffffffff8100d21a>] child_rip+0xa/0x20 >> [<ffffffffffffffff>] 0xffffffffffffffff > > Same as above, does it disappear with subsequent scans? This doesn't > look immediately like a false positive, it needs a bit more > investigation. >
No they seem to be permanent - but the hex dump area is changing for some of those objects. That's why I assume they are false positives.
Zdenek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |