The patch titled /proc/kcore: work around a BUG() has been added to the -mm tree. Its filename is proc-kcore-work-around-a-bug.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: /proc/kcore: work around a BUG() From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Works around a BUG() which is triggered when the kernel accesses holes in vmalloc regions. BUG: unable to handle kernel paging request at fa54c000 IP: [<c04f687a>] read_kcore+0x260/0x31a *pde = 3540b067 *pte = 00000000 Oops: 0000 [#1] SMP last sysfs file: /sys/devices/pci0000:00/0000:00:1c.2/0000:03:00.0/ieee80211/phy0/rfkill0/state Modules linked in: fuse sco bridge stp llc bnep l2cap bluetooth sunrpc nf_conntrack_ftp ip6t_REJECT nf_conntrack_ipv6 ip6table_filter ip6_tables ipv6 cpufreq_ondemand acpi_cpufreq dm_multipath uinput usb_storage arc4 ecb snd_hda_codec_realtek snd_hda_intel ath5k snd_hda_codec snd_hwdep iTCO_wdt snd_pcm iTCO_vendor_support pcspkr i2c_i801 mac80211 joydev snd_timer serio_raw r8169 snd soundcore mii snd_page_alloc ath cfg80211 ata_generic i915 drm i2c_algo_bit i2c_core video output [last unloaded: scsi_wait_scan] Sep 4 12:45:16 tuxedu kernel: Pid: 2266, comm: cat Not tainted (2.6.31-rc8 #2) Joybook Lite U101 EIP: 0060:[<c04f687a>] EFLAGS: 00010286 CPU: 0 EIP is at read_kcore+0x260/0x31a EAX: f5e5ea00 EBX: fa54d000 ECX: 00000400 EDX: 00001000 ESI: fa54c000 EDI: f44ad000 EBP: e4533f4c ESP: e4533f24 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 Process cat (pid: 2266, ti=e4532000 task=f09d19a0 task.ti=e4532000) Stack: 00005000 00000000 f44ad000 09d9c000 00003000 fa54c000 00001000 f6d16f60 e4520b80 fffffffb e4533f70 c04ef8eb e4533f98 00008000 09d97000 c04f661a e4520b80 09d97000 c04ef88c e4533f8c c04ba531 e4533f98 c04c0930 e4520b80 Call Trace: [<c04ef8eb>] ? proc_reg_read+0x5f/0x73 [<c04f661a>] ? read_kcore+0x0/0x31a [<c04ef88c>] ? proc_reg_read+0x0/0x73 [<c04ba531>] ? vfs_read+0x82/0xe1 [<c04c0930>] ? path_put+0x1a/0x1d [<c04ba62e>] ? sys_read+0x40/0x62 [<c0403298>] ? sysenter_do_call+0x12/0x2d Code: 39 f3 89 ca 0f 43 f3 89 fb 29 f2 29 f3 39 cf 0f 46 d3 29 55 dc 8d 1c 32 f6 40 0c 01 75 18 89 d1 89 f7 c1 e9 02 2b 7d ec 03 7d e0 <f3> a5 89 d1 83 e1 03 74 02 f3 a4 8b 00 83 7d dc 00 74 04 85 c0 EIP: [<c04f687a>] read_kcore+0x260/0x31a SS:ESP 0068:e4533f24 CR2: 00000000fa54c000 To access vmalloc area which may have memory holes, copy_from_user is useful. So this: # cat /proc/kcore > /dev/null will not panic. This is a minimal fix, suitable for 2.6.30.x and 2.6.31. More extensive /proc/kcore changes are planned for 2.6.32. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Tested-by: Nick Craig-Wood <nick@xxxxxxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx> Reported-by: <kbowa@xxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/kcore.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff -puN fs/proc/kcore.c~proc-kcore-work-around-a-bug fs/proc/kcore.c --- a/fs/proc/kcore.c~proc-kcore-work-around-a-bug +++ a/fs/proc/kcore.c @@ -361,7 +361,13 @@ read_kcore(struct file *file, char __use /* don't dump ioremap'd stuff! (TA) */ if (m->flags & VM_IOREMAP) continue; - memcpy(elf_buf + (vmstart - start), + /* + * we may access memory holes, then use + * ex_table. checking return value just for + * avoid warnings. + */ + vmsize = __copy_from_user_inatomic( + elf_buf + (vmstart - start), (char *)vmstart, vmsize); } read_unlock(&vmlist_lock); _ Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are proc-kcore-work-around-a-bug.patch mm-clean-up-page_remove_rmap.patch vmscan-throttle-direct-reclaim-when-too-many-pages-are-isolated-already.patch mm-remove-__addsub_zone_page_state.patch vmscan-dont-attempt-to-reclaim-anon-page-in-lumpy-reclaim-when-no-swap-space-is-avilable.patch ksm-add-mmu_notifier-set_pte_at_notify.patch ksm-first-tidy-up-madvise_vma.patch ksm-define-madv_mergeable-and-madv_unmergeable.patch ksm-the-mm-interface-to-ksm.patch ksm-no-debug-in-page_dup_rmap.patch ksm-identify-pageksm-pages.patch ksm-kernel-samepage-merging.patch ksm-prevent-mremap-move-poisoning.patch ksm-change-copyright-message.patch ksm-change-ksm-nice-level-to-be-5.patch vmalloc-unmap-vmalloc-area-after-hiding-it.patch kcore-fix-vread-vwrite-to-be-aware-of-holes.patch kcore-fix-vread-vwrite-to-be-aware-of-holes-update.patch kcore-proc-kcore-should-use-vread.patch mm-add_to_swap_cache-must-not-sleep.patch mm-add_to_swap_cache-does-not-return-eexist.patch memory-hotplug-fix-updating-of-num_physpages-for-hot-plugged-memory.patch mm-vmscan-rename-zone_nr_pages-to-zone_lru_nr_pages.patch mm-do-batched-scans-for-mem_cgroup.patch oom-move-oom_adj-value-from-task_struct-to-signal_struct.patch oom-make-oom_score-to-per-process-value.patch oom-oom_kill-doesnt-kill-vfork-parentor-child.patch oom-fix-oom_adjust_write-input-sanity-check.patch mm-fix-numa-accounting-in-numastattxt.patch kcore-fix-proc-kcores-statst_size.patch kcore-use-usual-list-for-kclist.patch kcore-add-kclist-types.patch kcore-register-vmalloc-area-in-generic-way.patch kcore-register-text-area-in-generic-way.patch walk-system-ram-range.patch kcore-use-registerd-physmem-information.patch kcore-register-vmemmap-range.patch kcore-register-vmemmap-range-fix.patch kcore-register-module-area-in-generic-way.patch cgroups-support-named-cgroups-hierarchies.patch cgroups-move-the-cgroup-debug-subsys-into-cgroupc-to-access-internal-state.patch cgroups-add-a-back-pointer-from-struct-cg_cgroup_link-to-struct-cgroup.patch cgroups-allow-cgroup-hierarchies-to-be-created-with-no-bound-subsystems.patch memcg-remove-the-overhead-associated-with-the-root-cgroup.patch memcg-remove-the-overhead-associated-with-the-root-cgroup-fix.patch memcg-remove-the-overhead-associated-with-the-root-cgroup-fix-2.patch memcg-add-comments-explaining-memory-barriers.patch memcg-add-comments-explaining-memory-barriers-checkpatch-fixes.patch memory-controller-soft-limit-documentation-v9.patch memory-controller-soft-limit-interface-v9.patch memory-controller-soft-limit-organize-cgroups-v9.patch memory-controller-soft-limit-organize-cgroups-v9-fix.patch memory-controller-soft-limit-refactor-reclaim-flags-v9.patch memory-controller-soft-limit-reclaim-on-contention-v9.patch memory-controller-soft-limit-reclaim-on-contention-v9-fix.patch memory-controller-soft-limit-reclaim-on-contention-v9-fix-softlimit-css-refcnt-handling.patch memory-controller-soft-limit-reclaim-on-contention-v9-fix-softlimit-css-refcnt-handling-fix.patch memcg-improve-resource-counter-scalability.patch memcg-improve-resource-counter-scalability-v5.patch memcg-show-swap-usage-in-stat-file.patch memcg-show-swap-usage-in-stat-file-fix.patch do_wait-wakeup-optimization-fix-child_wait_callback-eligible_child-usage.patch do_wait-wakeup-optimization-simplify-task_pid_type.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html