Hi Sahitya,

Node manager was initialized after segment manager's initialization,
so f2fs_available_free_memory() called from issue_discard_thread()
may access invalid nm_i pointer, could you please check and fix
this case?

On 2021/3/16 12:58, kernel test robot wrote:


Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: ab2dbddfd064f2078a7099e4d65cce54f5ef5e71 ("[PATCH v2] f2fs: allow to change 
discard policy based on cached discard cmds")
url: 
https://github.com/0day-ci/linux/commits/Sahitya-Tummala/f2fs-allow-to-change-discard-policy-based-on-cached-discard-cmds/20210311-170257


in testcase: ltp
version: ltp-x86_64-14c1f76-1_20210315
with following parameters:

        disk: 1HDD
        fs: f2fs
        test: io
        ucode: 0x21

test-description: The LTP testsuite contains a collection of tools for testing 
the Linux kernel and related features.
test-url: http://linux-test-project.github.io/


on test machine: 4 threads Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz with 8G 
memory

caused below changes (please refer to attached dmesg/kmsg for entire 
log/backtrace):



If you fix the issue, kindly add following tag
Reported-by: kernel test robot <oliver.s...@intel.com>


[   38.378402] BUG: kernel NULL pointer dereference, address: 0000000000000010
[   38.378526] #PF: supervisor read access in kernel mode
[   38.378610] #PF: error_code(0x0000) - not-present page
[   38.378694] PGD 0 P4D 0
[   38.378739] Oops: 0000 [#1] SMP PTI
[   38.378799] CPU: 2 PID: 2436 Comm: f2fs_discard-8: Not tainted 
5.12.0-rc2-00001-gab2dbddfd064 #1
[   38.378940] Hardware name: Hewlett-Packard p6-1451cx/2ADA, BIOS 8.15 
02/05/2013
[   38.379057] RIP: 0010:f2fs_available_free_memory 
(kbuild/src/consumer/fs/f2fs/node.c:96) f2fs
[ 38.379237] Code: 04 00 00 48 0f af d6 48 be c3 f5 28 5c 8f c2 f5 28 48 c1 ea 02 48 
89 d0 48 f7 e6 48 c1 ea 03 48 39 ca 0f 97 c0 e9 af fe ff ff <41> 8b 54 24 10 49 
63 8d 94 20 00 00 48 0f af d6 48 be c3 f5 28 5c
All code
========
    0:  04 00                   add    $0x0,%al
    2:  00 48 0f                add    %cl,0xf(%rax)
    5:  af                      scas   %es:(%rdi),%eax
    6:  d6                      (bad)
    7:  48 be c3 f5 28 5c 8f    movabs $0x28f5c28f5c28f5c3,%rsi
    e:  c2 f5 28
   11:  48 c1 ea 02             shr    $0x2,%rdx
   15:  48 89 d0                mov    %rdx,%rax
   18:  48 f7 e6                mul    %rsi
   1b:  48 c1 ea 03             shr    $0x3,%rdx
   1f:  48 39 ca                cmp    %rcx,%rdx
   22:  0f 97 c0                seta   %al
   25:  e9 af fe ff ff          jmpq   0xfffffffffffffed9
   2a:* 41 8b 54 24 10          mov    0x10(%r12),%edx          <-- trapping 
instruction
   2f:  49 63 8d 94 20 00 00    movslq 0x2094(%r13),%rcx
   36:  48 0f af d6             imul   %rsi,%rdx
   3a:  48                      rex.W
   3b:  be c3 f5 28 5c          mov    $0x5c28f5c3,%esi

Code starting with the faulting instruction
===========================================
    0:  41 8b 54 24 10          mov    0x10(%r12),%edx
    5:  49 63 8d 94 20 00 00    movslq 0x2094(%r13),%rcx
    c:  48 0f af d6             imul   %rsi,%rdx
   10:  48                      rex.W
   11:  be c3 f5 28 5c          mov    $0x5c28f5c3,%esi
[   38.379531] RSP: 0018:ffffc900006f3dd8 EFLAGS: 00010246
[   38.379617] RAX: 0000000000000106 RBX: ffff888213317000 RCX: 00000000001e9c8c
[   38.379731] RDX: ffff88810c84b430 RSI: 00000000001e9c8c RDI: ffff88810c84b540
[   38.379844] RBP: 0000000000000006 R08: 0000000000000106 R09: ffff88821fb2bc58
[   38.379958] R10: 000000000000032e R11: ffff88821fb2a144 R12: 0000000000000000
[   38.380071] R13: ffff88820b7e4000 R14: 000000000000ea60 R15: 0000000000000000
[   38.380185] FS:  0000000000000000(0000) GS:ffff88821fb00000(0000) 
knlGS:0000000000000000
[   38.380315] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   38.380408] CR2: 0000000000000010 CR3: 000000021e00a003 CR4: 00000000001706e0
[   38.380522] Call Trace:
[   38.380619] ? del_timer_sync (kbuild/src/consumer/kernel/time/timer.c:1394)
[   38.380686] ? prepare_to_wait_event 
(kbuild/src/consumer/kernel/sched/wait.c:323 (discriminator 15))
[   38.380762] ? __next_timer_interrupt 
(kbuild/src/consumer/kernel/time/timer.c:1816)
[   38.380841] issue_discard_thread (kbuild/src/consumer/fs/f2fs/segment.c:1759 
(discriminator 1)) f2fs
[   38.380937] ? finish_wait (kbuild/src/consumer/kernel/sched/wait.c:403)
[   38.380997] ? __issue_discard_cmd 
(kbuild/src/consumer/fs/f2fs/segment.c:1722) f2fs
[   38.381094] kthread (kbuild/src/consumer/kernel/kthread.c:292)
[   38.381151] ? kthread_park (kbuild/src/consumer/kernel/kthread.c:245)
[   38.381213] ret_from_fork (kbuild/src/consumer/arch/x86/entry/entry_64.S:300)
[   38.381276] Modules linked in: dm_mod f2fs netconsole btrfs blake2b_generic 
xor zstd_compress raid6_pq libcrc32c sd_mod t10_pi sg intel_rapl_msr 
intel_rapl_common i915 x86_pkg_temp_thermal intel_powerclamp coretemp intel_gtt 
crct10dif_pclmul crc32_pclmul drm_kms_helper crc32c_intel usb_storage 
ghash_clmulni_intel syscopyarea rapl ahci libahci sysfillrect sysimgblt 
fb_sys_fops ipmi_devintf ipmi_msghandler intel_cstate drm libata intel_uncore 
mei_me mei video ip_tables
[   38.381939] CR2: 0000000000000010
[   38.381996] ---[ end trace d47b1e3f3cb425e8 ]---
[   38.382072] RIP: 0010:f2fs_available_free_memory 
(kbuild/src/consumer/fs/f2fs/node.c:96) f2fs
[ 38.382188] Code: 04 00 00 48 0f af d6 48 be c3 f5 28 5c 8f c2 f5 28 48 c1 ea 02 48 
89 d0 48 f7 e6 48 c1 ea 03 48 39 ca 0f 97 c0 e9 af fe ff ff <41> 8b 54 24 10 49 
63 8d 94 20 00 00 48 0f af d6 48 be c3 f5 28 5c
All code
========
    0:  04 00                   add    $0x0,%al
    2:  00 48 0f                add    %cl,0xf(%rax)
    5:  af                      scas   %es:(%rdi),%eax
    6:  d6                      (bad)
    7:  48 be c3 f5 28 5c 8f    movabs $0x28f5c28f5c28f5c3,%rsi
    e:  c2 f5 28
   11:  48 c1 ea 02             shr    $0x2,%rdx
   15:  48 89 d0                mov    %rdx,%rax
   18:  48 f7 e6                mul    %rsi
   1b:  48 c1 ea 03             shr    $0x3,%rdx
   1f:  48 39 ca                cmp    %rcx,%rdx
   22:  0f 97 c0                seta   %al
   25:  e9 af fe ff ff          jmpq   0xfffffffffffffed9
   2a:* 41 8b 54 24 10          mov    0x10(%r12),%edx          <-- trapping 
instruction
   2f:  49 63 8d 94 20 00 00    movslq 0x2094(%r13),%rcx
   36:  48 0f af d6             imul   %rsi,%rdx
   3a:  48                      rex.W
   3b:  be c3 f5 28 5c          mov    $0x5c28f5c3,%esi

Code starting with the faulting instruction
===========================================
    0:  41 8b 54 24 10          mov    0x10(%r12),%edx
    5:  49 63 8d 94 20 00 00    movslq 0x2094(%r13),%rcx
    c:  48 0f af d6             imul   %rsi,%rdx
   10:  48                      rex.W
   11:  be c3 f5 28 5c          mov    $0x5c28f5c3,%esi


To reproduce:

         git clone https://github.com/intel/lkp-tests.git
         cd lkp-tests
         bin/lkp install                job.yaml  # job file is attached in 
this email
         bin/lkp split-job --compatible job.yaml
         bin/lkp run                    compatible-job.yaml



---
0DAY/LKP+ Test Infrastructure                   Open Source Technology Center
https://lists.01.org/hyperkitty/list/l...@lists.01.org       Intel Corporation

Thanks,
Oliver Sang

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