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Lklabs lectures intro #5

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merged 7 commits into from
Feb 20, 2018
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@tavip tavip commented Feb 20, 2018

Add support for lectures and add an introductory lecture that is split in two parts: one that is specific to the SO2 course @ UPB and one that is generic.

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tavip commented Feb 20, 2018

@dbaluta @razvand Please review, I've already pushed the build to https://linux-kernel-labs.github.io to make it easier to review the final product.

* Software RAID
* Teme “extra”
* Filesystem driver - hackaton
* E100 driver - Ixia challenge
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@razvand I think we should add file system assignment as Ixia Challenge.

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@dbaluta , was that the decision? Let's talk with the assignment team.

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@dbaluta dbaluta Feb 20, 2018

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@razvand we didn't reach a conclusion on this. My proposal is to use the file system assigment for Ixia challenge. @alexandrasandulescu what do you think?

In this case we will use fs assigment during Ixia Challenge and after that as a bonus assignment to demonstrate fs lectures/labs.

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@razvand @dbaluta
using fs for Ixia Challenge is ok considering it was modified by Adrian and lots of solutions of the previous version are on the internet. We should encourage students to participate in this competition. We could also let students solve it during normal assignment time like scheduled by Razvan.

I suggest using E100 for hackathon because it is also a complex and useful assignment.

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@alexandrasandulescu , @dbaluta , I agree to using the fs assignment as the Ixia challenge and to making a hackathon for the e100 assignment.

| kernel programming (SO2) |
+--------------------------+


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Would be nice to add also the "hardware" part with PM, CN1, CN2, PL (Programare Logica).

[#hypervisor]_ control the CPU while code that runs in user mode has
certain limitations. For example, local CPU interrupts can only be
disabled or enable while running in kernel mode. If such an operation
is attempted while running in user mode a exception will be generated
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s/a exception/an exception.

There are a class of operating systems that (used to) claim to be
hybrid kernels, in between monolithic and micro-kernels (e.g. Windows,
Max OS X). However, since all of the typical monolithic services run
in kernel-mode in these operating systems, there is little merit to
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s/Max OS X/Mac OS X, i guess.

0xC0000000 | | ^
| | | User space
| | |
0x00000000 +--------------+ v
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Aici ar trebui sa facem partea de "user space" mai mare. Cel putin pe slide se vede foarte mica si nici nu arata ca am avea un split 1/3.

CPU Scalability
---------------

CPU scalability refers to wow well does that performance scales with
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s/wow/how

@@ -12,7 +17,7 @@ each topic there are two parts:
is presented with a starting coding skeleton and with in-depth tips
on how to solve the exercises

They are based on the labs of the `Operatings Systems 2
This content is based on the `Operatings Systems 2
<http://ocw.cs.pub.ro/courses/so2>`_ course, Computer Science
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The Computer Science and Engineering Department, the Faculty of Automatic Control and Computers, University POLITEHNICA of Bucharest.

=========

* wiki: http://ocw.cs.pub.ro/courses/so2
* NeedToKnow: http://ocw.cs.pub.ro/courses/so2/need-to-know
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+* Linux Kernel Labs: https://linux-kernel-labs.github.io/

Community
=========

* laboratoarele (din wiki) sunt editabile
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Since we are going to add lectures change the top level directory name
from labs to teaching/labs.

Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>
Enable hieroglyph extension if it is installed on the host and add a
slides documentation target.

Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>
Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>
This is based on the psphinxcontrib.ditaa pip package and we add it
localy since we need some fixes to properly render images in
hieroglpyh slides.

Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>
Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>
Add reqirements.txt and run pip in the doc target to make sure we have
all required sphinx dependencies.

Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>
@tavip tavip force-pushed the lklabs-lectures-intro branch 2 times, most recently from f7a8865 to 23f1e06 Compare February 20, 2018 15:06
This is split into two parts: one the is specific to cs.pub.ro and
another one that is generic.

Signed-off-by: Octavian Purdila <tavi@cs.pub.ro>
@tavip tavip merged commit 414c483 into linux-kernel-labs:master Feb 20, 2018
dbaluta referenced this pull request in dbaluta/linux Jul 8, 2019
Ido Schimmel says:

====================
mlxsw: Various fixes

This patchset contains various fixes for mlxsw.

Patch #1 fixes an hash polarization problem when a nexthop device is a
LAG device. This is caused by the fact that the same seed is used for
the LAG and ECMP hash functions.

Patch #2 fixes an issue in which the driver fails to refresh a nexthop
neighbour after it becomes dead. This prevents the nexthop from ever
being written to the adjacency table and used to forward traffic. Patch

Patch #4 fixes a wrong extraction of TOS value in flower offload code.
Patch #5 is a test case.

Patch #6 works around a buffer issue in Spectrum-2 by reducing the
default sizes of the shared buffer pools.

Patch linux-kernel-labs#7 prevents prio-tagged packets from entering the switch when PVID
is removed from the bridge port.

Please consider patches #2, #4 and #6 for 5.1.y
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
dbaluta referenced this pull request in dbaluta/linux Jul 8, 2019
Puts range check before dereferencing the pointer.

Reproducer:

  # echo stacktrace > trace_options
  # echo 1 > events/enable
  # cat trace > /dev/null

KASAN report:

  ==================================================================
  BUG: KASAN: use-after-free in trace_stack_print+0x26b/0x2c0
  Read of size 8 at addr ffff888069d20000 by task cat/1953

  CPU: 0 PID: 1953 Comm: cat Not tainted 5.2.0-rc3+ #5
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
  Call Trace:
   dump_stack+0x8a/0xce
   print_address_description+0x60/0x224
   ? trace_stack_print+0x26b/0x2c0
   ? trace_stack_print+0x26b/0x2c0
   __kasan_report.cold+0x1a/0x3e
   ? trace_stack_print+0x26b/0x2c0
   kasan_report+0xe/0x20
   trace_stack_print+0x26b/0x2c0
   print_trace_line+0x6ea/0x14d0
   ? tracing_buffers_read+0x700/0x700
   ? trace_find_next_entry_inc+0x158/0x1d0
   s_show+0xea/0x310
   seq_read+0xaa7/0x10e0
   ? seq_escape+0x230/0x230
   __vfs_read+0x7c/0x100
   vfs_read+0x16c/0x3a0
   ksys_read+0x121/0x240
   ? kernel_write+0x110/0x110
   ? perf_trace_sys_enter+0x8a0/0x8a0
   ? syscall_slow_exit_work+0xa9/0x410
   do_syscall_64+0xb7/0x390
   ? prepare_exit_to_usermode+0x165/0x200
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f867681f910
  Code: b6 fe ff ff 48 8d 3d 0f be 08 00 48 83 ec 08 e8 06 db 01 00 66 0f 1f 44 00 00 83 3d f9 2d 2c 00 00 75 10 b8 00 00 00 00 04
  RSP: 002b:00007ffdabf23488 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
  RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f867681f910
  RDX: 0000000000020000 RSI: 00007f8676cde000 RDI: 0000000000000003
  RBP: 00007f8676cde000 R08: ffffffffffffffff R09: 0000000000000000
  R10: 0000000000000871 R11: 0000000000000246 R12: 00007f8676cde000
  R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000000ec0

  Allocated by task 1214:
   save_stack+0x1b/0x80
   __kasan_kmalloc.constprop.0+0xc2/0xd0
   kmem_cache_alloc+0xaf/0x1a0
   getname_flags+0xd2/0x5b0
   do_sys_open+0x277/0x5a0
   do_syscall_64+0xb7/0x390
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

  Freed by task 1214:
   save_stack+0x1b/0x80
   __kasan_slab_free+0x12c/0x170
   kmem_cache_free+0x8a/0x1c0
   putname+0xe1/0x120
   do_sys_open+0x2c5/0x5a0
   do_syscall_64+0xb7/0x390
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

  The buggy address belongs to the object at ffff888069d20000
   which belongs to the cache names_cache of size 4096
  The buggy address is located 0 bytes inside of
   4096-byte region [ffff888069d20000, ffff888069d21000)
  The buggy address belongs to the page:
  page:ffffea0001a74800 refcount:1 mapcount:0 mapping:ffff88806ccd1380 index:0x0 compound_mapcount: 0
  flags: 0x100000000010200(slab|head)
  raw: 0100000000010200 dead000000000100 dead000000000200 ffff88806ccd1380
  raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   ffff888069d1ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffff888069d1ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffff888069d20000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                     ^
   ffff888069d20080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
   ffff888069d20100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ==================================================================

Link: http://lkml.kernel.org/r/20190610040016.5598-1-devel@etsukata.com

Fixes: 4285f2f ("tracing: Remove the ULONG_MAX stack trace hackery")
Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
dbaluta referenced this pull request in dbaluta/linux Jul 23, 2019
It is possible for an irq triggered by channel0 to be received later
after clks are disabled once firmware loaded during sdma probe. If
that happens then clearing them by writing to SDMA_H_INTR won't work
and the kernel will hang processing infinite interrupts. Actually,
don't need interrupt triggered on channel0 since it's pollling
SDMA_H_STATSTOP to know channel0 done rather than interrupt in
current code, just clear BD_INTR to disable channel0 interrupt to
avoid the above case.
This issue was brought by commit 1d069bf ("dmaengine: imx-sdma:
ack channel 0 IRQ in the interrupt handler") which didn't take care
the above case.

Fixes: 1d069bf ("dmaengine: imx-sdma: ack channel 0 IRQ in the interrupt handler")
Cc: stable@vger.kernel.org #5.0+
Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reported-by: Sven Van Asbroeck <thesven73@gmail.com>
Tested-by: Sven Van Asbroeck <thesven73@gmail.com>
Reviewed-by: Michael Olbrich <m.olbrich@pengutronix.de>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dbaluta referenced this pull request in dbaluta/linux Aug 9, 2019
This reverts commit 3342ce3, as there is no need for this separate
property and it breaks compatibility with existing devicetree files
(arch/arm64/boot/dts/freescale/imx8mq.dtsi).

CC: stable@vger.kernel.org #5.2
Fixes: 3342ce3 ("usb: usb251xb: Add US lanes inversion dts-bindings")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20190719084407.28041-1-l.stach@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dbaluta referenced this pull request in dbaluta/linux Aug 9, 2019
This property isn't needed and not yet used anywhere. The swap-dx-lanes
property is perfectly fine for doing the swap on the upstream port
lanes.

CC: stable@vger.kernel.org #5.2
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20190719084407.28041-2-l.stach@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dbaluta referenced this pull request in dbaluta/linux Aug 9, 2019
This is a partial revert of 73d31de "usb: usb251xb: Create a ports
field collector method", which broke a existing devicetree
(arch/arm64/boot/dts/freescale/imx8mq.dtsi).

There is no reason why the swap-dx-lanes property should not apply to
the upstream port. The reason given in the breaking commit was that it's
inconsitent with respect to other port properties, but in fact it is not.
All other properties which only apply to the downstream ports explicitly
reject port 0, so there is pretty strong precedence that the driver
referred to the upstream port as port 0. So there is no inconsistency in
this property at all, other than the swapping being also applicable to
the upstream port.

CC: stable@vger.kernel.org #5.2
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20190719084407.28041-3-l.stach@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dbaluta referenced this pull request in dbaluta/linux Sep 28, 2019
KASAN report this:

BUG: unable to handle kernel paging request at fffffbfff834f001
PGD 237fe8067 P4D 237fe8067 PUD 237e64067 PMD 1c968d067 PTE 0
Oops: 0000 [#1] SMP KASAN PTI
CPU: 1 PID: 8871 Comm: syz-executor.0 Tainted: G         C        5.0.0+ #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
RIP: 0010:strcmp+0x31/0xa0 lib/string.c:328
Code: 00 00 00 00 fc ff df 55 53 48 83 ec 08 eb 0a 84 db 48 89 ef 74 5a 4c 89 e6 48 89 f8 48 89 fa 48 8d 6f 01 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 04 84 c0 75 50 48 89 f0 48 89 f2 0f b6 5d
RSP: 0018:ffff8881e0c57800 EFLAGS: 00010246
RAX: 1ffffffff834f001 RBX: ffffffffc1a78000 RCX: ffffffff827b9503
RDX: 0000000000000000 RSI: ffffffffc1a40008 RDI: ffffffffc1a78008
RBP: ffffffffc1a78009 R08: fffffbfff6a92195 R09: fffffbfff6a92195
R10: ffff8881e0c578b8 R11: fffffbfff6a92194 R12: ffffffffc1a40008
R13: dffffc0000000000 R14: ffffffffc1a3e470 R15: ffffffffc1a40000
FS:  00007fdcc02ff700(0000) GS:ffff8881f7300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff834f001 CR3: 00000001b3134003 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 genl_family_find_byname+0x7f/0xf0 net/netlink/genetlink.c:104
 genl_register_family+0x1e1/0x1070 net/netlink/genetlink.c:333
 ? 0xffffffffc1978000
 hwsim_init_module+0x6a/0x1000 [mac802154_hwsim]
 ? 0xffffffffc1978000
 ? 0xffffffffc1978000
 ? 0xffffffffc1978000
 do_one_initcall+0xbc/0x47d init/main.c:887
 do_init_module+0x1b5/0x547 kernel/module.c:3456
 load_module+0x6405/0x8c10 kernel/module.c:3804
 __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
 do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x462e99
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fdcc02fec58 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99
RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003
RBP: 00007fdcc02fec70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdcc02ff6bc
R13: 00000000004bcefa R14: 00000000006f6fb0 R15: 0000000000000004
Modules linked in: mac802154_hwsim(+) mac802154 ieee802154 speakup(C) rc_proteus_2309 rtc_rk808 streebog_generic rds vboxguest madera_spi madera da9052_wdt mISDN_core ueagle_atm usbatm atm ir_imon_decoder scsi_transport_sas rc_dntv_live_dvb_t panel_samsung_s6d16d0 drm drm_panel_orientation_quirks lib80211 fb_agm1264k_fl(C) gspca_pac7302 gspca_main videobuf2_v4l2 soundwire_intel_init i2c_dln2 dln2 usbcore hid_gaff 88pm8607 nfnetlink axp20x_i2c axp20x uio pata_marvell pmbus_core snd_sonicvibes gameport snd_pcm snd_opl3_lib snd_timer snd_hwdep snd_mpu401_uart snd_rawmidi snd_seq_device snd soundcore rtc_ds1511 rtc_ds1742 vsock dwc_xlgmac rtc_rx8010 libphy twofish_x86_64_3way twofish_x86_64 twofish_common ad5696_i2c ad5686 lp8788_charger cxd2880_spi dvb_core videobuf2_common videodev media videobuf2_vmalloc videobuf2_memops fbtft(C) sysimgblt sysfillrect syscopyarea fb_sys_fops janz_ican3 firewire_net firewire_core crc_itu_t spi_slave_system_control i2c_matroxfb i2c_algo_bit
 matroxfb_base fb fbdev matroxfb_DAC1064 matroxfb_accel cfbcopyarea cfbimgblt cfbfillrect matroxfb_Ti3026 matroxfb_g450 g450_pll matroxfb_misc leds_blinkm ti_dac7311 intel_spi_pci intel_spi spi_nor hid_elan hid async_tx rc_cinergy_1400 rc_core intel_ishtp kxcjk_1013 industrialio_triggered_buffer kfifo_buf can_dev intel_th spi_pxa2xx_platform pata_artop vme_ca91cx42 gb_gbphy(C) greybus(C) industrialio mptbase st_drv cmac ttpci_eeprom via_wdt gpio_xra1403 mtd iptable_security iptable_raw iptable_mangle iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter bpfilter ip6_vti ip_vti ip_gre ipip sit tunnel4 ip_tunnel hsr veth netdevsim vxcan batman_adv cfg80211 rfkill chnl_net caif nlmon dummy team bonding vcan bridge stp llc ip6_gre gre ip6_tunnel tunnel6 tun joydev mousedev ppdev kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel aes_x86_64 input_leds crypto_simd cryptd glue_helper ide_pci_generic piix psmouse
 ide_core serio_raw ata_generic i2c_piix4 pata_acpi parport_pc parport floppy rtc_cmos intel_agp intel_gtt agpgart sch_fq_codel ip_tables x_tables sha1_ssse3 sha1_generic ipv6 [last unloaded: speakup]
Dumping ftrace buffer:
   (ftrace buffer empty)
CR2: fffffbfff834f001
---[ end trace 5aa772c793e0e971 ]---
RIP: 0010:strcmp+0x31/0xa0 lib/string.c:328
Code: 00 00 00 00 fc ff df 55 53 48 83 ec 08 eb 0a 84 db 48 89 ef 74 5a 4c 89 e6 48 89 f8 48 89 fa 48 8d 6f 01 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 04 84 c0 75 50 48 89 f0 48 89 f2 0f b6 5d
RSP: 0018:ffff8881e0c57800 EFLAGS: 00010246
RAX: 1ffffffff834f001 RBX: ffffffffc1a78000 RCX: ffffffff827b9503
RDX: 0000000000000000 RSI: ffffffffc1a40008 RDI: ffffffffc1a78008
RBP: ffffffffc1a78009 R08: fffffbfff6a92195 R09: fffffbfff6a92195
R10: ffff8881e0c578b8 R11: fffffbfff6a92194 R12: ffffffffc1a40008
R13: dffffc0000000000 R14: ffffffffc1a3e470 R15: ffffffffc1a40000
FS:  00007fdcc02ff700(0000) GS:ffff8881f7300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfff834f001 CR3: 00000001b3134003 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554

The error handing path misplace the cleanup in hwsim_init_module,
switch the two cleanup functions to fix above issues.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: f25da51 ("ieee802154: hwsim: add replacement for fakelb")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
dbaluta referenced this pull request in dbaluta/linux Sep 28, 2019
Calling ceph_buffer_put() in fill_inode() may result in freeing the
i_xattrs.blob buffer while holding the i_ceph_lock.  This can be fixed by
postponing the call until later, when the lock is released.

The following backtrace was triggered by fstests generic/070.

  BUG: sleeping function called from invalid context at mm/vmalloc.c:2283
  in_atomic(): 1, irqs_disabled(): 0, pid: 3852, name: kworker/0:4
  6 locks held by kworker/0:4/3852:
   #0: 000000004270f6bb ((wq_completion)ceph-msgr){+.+.}, at: process_one_work+0x1b8/0x5f0
   #1: 00000000eb420803 ((work_completion)(&(&con->work)->work)){+.+.}, at: process_one_work+0x1b8/0x5f0
   #2: 00000000be1c53a4 (&s->s_mutex){+.+.}, at: dispatch+0x288/0x1476
   #3: 00000000559cb958 (&mdsc->snap_rwsem){++++}, at: dispatch+0x2eb/0x1476
   #4: 000000000d5ebbae (&req->r_fill_mutex){+.+.}, at: dispatch+0x2fc/0x1476
   #5: 00000000a83d0514 (&(&ci->i_ceph_lock)->rlock){+.+.}, at: fill_inode.isra.0+0xf8/0xf70
  CPU: 0 PID: 3852 Comm: kworker/0:4 Not tainted 5.2.0+ torvalds#441
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-prebuilt.qemu.org 04/01/2014
  Workqueue: ceph-msgr ceph_con_workfn
  Call Trace:
   dump_stack+0x67/0x90
   ___might_sleep.cold+0x9f/0xb1
   vfree+0x4b/0x60
   ceph_buffer_release+0x1b/0x60
   fill_inode.isra.0+0xa9b/0xf70
   ceph_fill_trace+0x13b/0xc70
   ? dispatch+0x2eb/0x1476
   dispatch+0x320/0x1476
   ? __mutex_unlock_slowpath+0x4d/0x2a0
   ceph_con_workfn+0xc97/0x2ec0
   ? process_one_work+0x1b8/0x5f0
   process_one_work+0x244/0x5f0
   worker_thread+0x4d/0x3e0
   kthread+0x105/0x140
   ? process_one_work+0x5f0/0x5f0
   ? kthread_park+0x90/0x90
   ret_from_fork+0x3a/0x50

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
dbaluta referenced this pull request in dbaluta/linux Nov 15, 2019
The baseboard of the Logic PD i.MX6 development kit has a power
button routed which can both power down and power up the board.
It can also wake the board from sleep.  This functionality was
marked as disabled by default in imx6qdl.dtsi, so it needs to
be explicitly enabled for each board.

This patch enables the snvs power key again.

Signed-off-by: Adam Ford <aford173@gmail.com>
Fixes: 770856f ("ARM: dts: imx6qdl: Enable SNVS power key according to board design")
Cc: stable <stable@vger.kernel.org> #5.3+
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
dbaluta referenced this pull request in dbaluta/linux Jan 29, 2020
Ido Schimmel says:

====================
mlxsw: Various fixes

This patch set contains various fixes for mlxsw.

Patch #1 splits the init() callback between Spectrum-2 and Spectrum-3 in
order to avoid enforcing the same firmware version for both ASICs, as
this can't possibly work. Without this patch the driver cannot boot with
the Spectrum-3 ASIC.

Patches #2-#3 fix a long standing race condition that was recently
exposed while testing the driver on an emulator, which is very slow
compared to the actual hardware. The problem is explained in detail in
the commit messages.

Patch #4 fixes a selftest.

Patch #5 prevents offloaded qdiscs from presenting a non-zero backlog to
the user when the netdev is down. This is done by clearing the cached
backlog in the driver when the netdev goes down.

Patch #6 fixes qdisc statistics (backlog and tail drops) to also take
into account the multicast traffic classes.

v2:
* Patches #2-#3: use skb_cow_head() instead of skb_unshare() as
  suggested by Jakub. Remove unnecessary check regarding headroom
* Patches #5-#6: new
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
dbaluta referenced this pull request in dbaluta/linux Jun 17, 2020
This BUG halt was reported a while back, but the patch somehow got
missed:

PID: 2879   TASK: c16adaa0  CPU: 1   COMMAND: "sctpn"
 #0 [f418dd28] crash_kexec at c04a7d8c
 #1 [f418dd7c] oops_end at c0863e02
 #2 [f418dd90] do_invalid_op at c040aaca
 #3 [f418de28] error_code (via invalid_op) at c08631a5
    EAX: f34baac0  EBX: 00000090  ECX: f418deb0  EDX: f5542950  EBP: 00000000
    DS:  007b      ESI: f34ba800  ES:  007b      EDI: f418dea0  GS:  00e0
    CS:  0060      EIP: c046fa5e  ERR: ffffffff  EFLAGS: 00010286
 #4 [f418de5c] add_timer at c046fa5e
 #5 [f418de68] sctp_do_sm at f8db8c77 [sctp]
 #6 [f418df30] sctp_primitive_SHUTDOWN at f8dcc1b5 [sctp]
 linux-kernel-labs#7 [f418df48] inet_shutdown at c080baf9
 linux-kernel-labs#8 [f418df5c] sys_shutdown at c079eedf
 linux-kernel-labs#9 [f418df7] sys_socketcall at c079fe88
    EAX: ffffffda  EBX: 0000000d  ECX: bfceea90  EDX: 0937af98
    DS:  007b      ESI: 0000000c  ES:  007b      EDI: b7150ae4
    SS:  007b      ESP: bfceea7c  EBP: bfceeaa8  GS:  0033
    CS:  0073      EIP: b775c424  ERR: 00000066  EFLAGS: 00000282

It appears that the side effect that starts the shutdown timer was processed
multiple times, which can happen as multiple paths can trigger it.  This of
course leads to the BUG halt in add_timer getting called.

Fix seems pretty straightforward, just check before the timer is added if its
already been started.  If it has mod the timer instead to min(current
expiration, new expiration)

Its been tested but not confirmed to fix the problem, as the issue has only
occured in production environments where test kernels are enjoined from being
installed.  It appears to be a sane fix to me though.  Also, recentely,
Jere found a reproducer posted on list to confirm that this resolves the
issues

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yasevich <vyasevich@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: jere.leppanen@nokia.com
CC: marcelo.leitner@gmail.com
CC: netdev@vger.kernel.org
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
dbaluta referenced this pull request in dbaluta/linux Aug 10, 2020
devm_gpiod_get_index() doesn't return NULL but -ENOENT when the
requested GPIO doesn't exist,  leading to the following messages:

[    2.742468] gpiod_direction_input: invalid GPIO (errorpointer)
[    2.748147] can't set direction for gpio #2: -2
[    2.753081] gpiod_direction_input: invalid GPIO (errorpointer)
[    2.758724] can't set direction for gpio #3: -2
[    2.763666] gpiod_direction_output: invalid GPIO (errorpointer)
[    2.769394] can't set direction for gpio #4: -2
[    2.774341] gpiod_direction_input: invalid GPIO (errorpointer)
[    2.779981] can't set direction for gpio #5: -2
[    2.784545] ff000a20.serial: ttyCPM1 at MMIO 0xfff00a20 (irq = 39, base_baud = 8250000) is a CPM UART

Use devm_gpiod_get_index_optional() instead.

At the same time, handle the error case and properly exit
with an error.

Fixes: 97cbaf2 ("tty: serial: cpm_uart: Convert to use GPIO descriptors")
Cc: stable@vger.kernel.org
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/694a25fdce548c5ee8b060ef6a4b02746b8f25c0.1591986307.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dbaluta referenced this pull request in dbaluta/linux Feb 3, 2021
Like other tunneling interfaces, the bareudp doesn't need TXLOCK.
So, It is good to set the NETIF_F_LLTX flag to improve performance and
to avoid lockdep's false-positive warning.

Test commands:
    ip netns add A
    ip netns add B
    ip link add veth0 netns A type veth peer name veth1 netns B
    ip netns exec A ip link set veth0 up
    ip netns exec A ip a a 10.0.0.1/24 dev veth0
    ip netns exec B ip link set veth1 up
    ip netns exec B ip a a 10.0.0.2/24 dev veth1

    for i in {2..1}
    do
            let A=$i-1
            ip netns exec A ip link add bareudp$i type bareudp \
		    dstport $i ethertype ip
            ip netns exec A ip link set bareudp$i up
            ip netns exec A ip a a 10.0.$i.1/24 dev bareudp$i
            ip netns exec A ip r a 10.0.$i.2 encap ip src 10.0.$A.1 \
		    dst 10.0.$A.2 via 10.0.$i.2 dev bareudp$i

            ip netns exec B ip link add bareudp$i type bareudp \
		    dstport $i ethertype ip
            ip netns exec B ip link set bareudp$i up
            ip netns exec B ip a a 10.0.$i.2/24 dev bareudp$i
            ip netns exec B ip r a 10.0.$i.1 encap ip src 10.0.$A.2 \
		    dst 10.0.$A.1 via 10.0.$i.1 dev bareudp$i
    done
    ip netns exec A ping 10.0.2.2

Splat looks like:
[   96.992803][  T822] ============================================
[   96.993954][  T822] WARNING: possible recursive locking detected
[   96.995102][  T822] 5.10.0+ torvalds#819 Not tainted
[   96.995927][  T822] --------------------------------------------
[   96.997091][  T822] ping/822 is trying to acquire lock:
[   96.998083][  T822] ffff88810f753898 (_xmit_NONE#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1f52/0x2960
[   96.999813][  T822]
[   96.999813][  T822] but task is already holding lock:
[   97.001192][  T822] ffff88810c385498 (_xmit_NONE#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1f52/0x2960
[   97.002908][  T822]
[   97.002908][  T822] other info that might help us debug this:
[   97.004401][  T822]  Possible unsafe locking scenario:
[   97.004401][  T822]
[   97.005784][  T822]        CPU0
[   97.006407][  T822]        ----
[   97.007010][  T822]   lock(_xmit_NONE#2);
[   97.007779][  T822]   lock(_xmit_NONE#2);
[   97.008550][  T822]
[   97.008550][  T822]  *** DEADLOCK ***
[   97.008550][  T822]
[   97.010057][  T822]  May be due to missing lock nesting notation
[   97.010057][  T822]
[   97.011594][  T822] 7 locks held by ping/822:
[   97.012426][  T822]  #0: ffff888109a144f0 (sk_lock-AF_INET){+.+.}-{0:0}, at: raw_sendmsg+0x12f7/0x2b00
[   97.014191][  T822]  #1: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x249/0x2020
[   97.016045][  T822]  #2: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1fd/0x2960
[   97.017897][  T822]  #3: ffff88810c385498 (_xmit_NONE#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1f52/0x2960
[   97.019684][  T822]  #4: ffffffffbce2f600 (rcu_read_lock){....}-{1:2}, at: bareudp_xmit+0x31b/0x3690 [bareudp]
[   97.021573][  T822]  #5: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x249/0x2020
[   97.023424][  T822]  #6: ffffffffbce2f5a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1fd/0x2960
[   97.025259][  T822]
[   97.025259][  T822] stack backtrace:
[   97.026349][  T822] CPU: 3 PID: 822 Comm: ping Not tainted 5.10.0+ torvalds#819
[   97.027609][  T822] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[   97.029407][  T822] Call Trace:
[   97.030015][  T822]  dump_stack+0x99/0xcb
[   97.030783][  T822]  __lock_acquire.cold.77+0x149/0x3a9
[   97.031773][  T822]  ? stack_trace_save+0x81/0xa0
[   97.032661][  T822]  ? register_lock_class+0x1910/0x1910
[   97.033673][  T822]  ? register_lock_class+0x1910/0x1910
[   97.034679][  T822]  ? rcu_read_lock_sched_held+0x91/0xc0
[   97.035697][  T822]  ? rcu_read_lock_bh_held+0xa0/0xa0
[   97.036690][  T822]  lock_acquire+0x1b2/0x730
[   97.037515][  T822]  ? __dev_queue_xmit+0x1f52/0x2960
[   97.038466][  T822]  ? check_flags+0x50/0x50
[   97.039277][  T822]  ? netif_skb_features+0x296/0x9c0
[   97.040226][  T822]  ? validate_xmit_skb+0x29/0xb10
[   97.041151][  T822]  _raw_spin_lock+0x30/0x70
[   97.041977][  T822]  ? __dev_queue_xmit+0x1f52/0x2960
[   97.042927][  T822]  __dev_queue_xmit+0x1f52/0x2960
[   97.043852][  T822]  ? netdev_core_pick_tx+0x290/0x290
[   97.044824][  T822]  ? mark_held_locks+0xb7/0x120
[   97.045712][  T822]  ? lockdep_hardirqs_on_prepare+0x12c/0x3e0
[   97.046824][  T822]  ? __local_bh_enable_ip+0xa5/0xf0
[   97.047771][  T822]  ? ___neigh_create+0x12a8/0x1eb0
[   97.048710][  T822]  ? trace_hardirqs_on+0x41/0x120
[   97.049626][  T822]  ? ___neigh_create+0x12a8/0x1eb0
[   97.050556][  T822]  ? __local_bh_enable_ip+0xa5/0xf0
[   97.051509][  T822]  ? ___neigh_create+0x12a8/0x1eb0
[   97.052443][  T822]  ? check_chain_key+0x244/0x5f0
[   97.053352][  T822]  ? rcu_read_lock_bh_held+0x56/0xa0
[   97.054317][  T822]  ? ip_finish_output2+0x6ea/0x2020
[   97.055263][  T822]  ? pneigh_lookup+0x410/0x410
[   97.056135][  T822]  ip_finish_output2+0x6ea/0x2020
[ ... ]

Acked-by: Guillaume Nault <gnault@redhat.com>
Fixes: 571912c ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://lore.kernel.org/r/20201228152136.24215-1-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
dbaluta referenced this pull request in dbaluta/linux Feb 3, 2021
KASAN detect following BUG:
[  778.215311] ==================================================================
[  778.216696] BUG: KASAN: use-after-free in rnbd_srv_sess_dev_force_close+0x38/0x60 [rnbd_server]
[  778.219037] Read of size 8 at addr ffff88b1d6516c28 by task tee/8842

[  778.220500] CPU: 37 PID: 8842 Comm: tee Kdump: loaded Not tainted 5.10.0-pserver #5.10.0-1+feature+linux+next+20201214.1025+0910d71
[  778.220529] Hardware name: Supermicro Super Server/X11DDW-L, BIOS 3.3 02/21/2020
[  778.220555] Call Trace:
[  778.220609]  dump_stack+0x99/0xcb
[  778.220667]  ? rnbd_srv_sess_dev_force_close+0x38/0x60 [rnbd_server]
[  778.220715]  print_address_description.constprop.7+0x1e/0x230
[  778.220750]  ? freeze_kernel_threads+0x73/0x73
[  778.220896]  ? rnbd_srv_sess_dev_force_close+0x38/0x60 [rnbd_server]
[  778.220932]  ? rnbd_srv_sess_dev_force_close+0x38/0x60 [rnbd_server]
[  778.220994]  kasan_report.cold.9+0x37/0x7c
[  778.221066]  ? kobject_put+0x80/0x270
[  778.221102]  ? rnbd_srv_sess_dev_force_close+0x38/0x60 [rnbd_server]
[  778.221184]  rnbd_srv_sess_dev_force_close+0x38/0x60 [rnbd_server]
[  778.221240]  rnbd_srv_dev_session_force_close_store+0x6a/0xc0 [rnbd_server]
[  778.221304]  ? sysfs_file_ops+0x90/0x90
[  778.221353]  kernfs_fop_write+0x141/0x240
[  778.221451]  vfs_write+0x142/0x4d0
[  778.221553]  ksys_write+0xc0/0x160
[  778.221602]  ? __ia32_sys_read+0x50/0x50
[  778.221684]  ? lockdep_hardirqs_on_prepare+0x13d/0x210
[  778.221718]  ? syscall_enter_from_user_mode+0x1c/0x50
[  778.221821]  do_syscall_64+0x33/0x40
[  778.221862]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  778.221896] RIP: 0033:0x7f4affdd9504
[  778.221928] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 48 8d 05 f9 61 0d 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 41 54 49 89 d4 55 48 89 f5 53
[  778.221956] RSP: 002b:00007fffebb36b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  778.222011] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f4affdd9504
[  778.222038] RDX: 0000000000000002 RSI: 00007fffebb36c50 RDI: 0000000000000003
[  778.222066] RBP: 00007fffebb36c50 R08: 0000556a151aa600 R09: 00007f4affeb1540
[  778.222094] R10: fffffffffffffc19 R11: 0000000000000246 R12: 0000556a151aa520
[  778.222121] R13: 0000000000000002 R14: 00007f4affea6760 R15: 0000000000000002

[  778.222764] Allocated by task 3212:
[  778.223285]  kasan_save_stack+0x19/0x40
[  778.223316]  __kasan_kmalloc.constprop.7+0xc1/0xd0
[  778.223347]  kmem_cache_alloc_trace+0x186/0x350
[  778.223382]  rnbd_srv_rdma_ev+0xf16/0x1690 [rnbd_server]
[  778.223422]  process_io_req+0x4d1/0x670 [rtrs_server]
[  778.223573]  __ib_process_cq+0x10a/0x350 [ib_core]
[  778.223709]  ib_cq_poll_work+0x31/0xb0 [ib_core]
[  778.223743]  process_one_work+0x521/0xa90
[  778.223773]  worker_thread+0x65/0x5b0
[  778.223802]  kthread+0x1f2/0x210
[  778.223833]  ret_from_fork+0x22/0x30

[  778.224296] Freed by task 8842:
[  778.224800]  kasan_save_stack+0x19/0x40
[  778.224829]  kasan_set_track+0x1c/0x30
[  778.224860]  kasan_set_free_info+0x1b/0x30
[  778.224889]  __kasan_slab_free+0x108/0x150
[  778.224919]  slab_free_freelist_hook+0x64/0x190
[  778.224947]  kfree+0xe2/0x650
[  778.224982]  rnbd_destroy_sess_dev+0x2fa/0x3b0 [rnbd_server]
[  778.225011]  kobject_put+0xda/0x270
[  778.225046]  rnbd_srv_sess_dev_force_close+0x30/0x60 [rnbd_server]
[  778.225081]  rnbd_srv_dev_session_force_close_store+0x6a/0xc0 [rnbd_server]
[  778.225111]  kernfs_fop_write+0x141/0x240
[  778.225140]  vfs_write+0x142/0x4d0
[  778.225169]  ksys_write+0xc0/0x160
[  778.225198]  do_syscall_64+0x33/0x40
[  778.225227]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[  778.226506] The buggy address belongs to the object at ffff88b1d6516c00
                which belongs to the cache kmalloc-512 of size 512
[  778.227464] The buggy address is located 40 bytes inside of
                512-byte region [ffff88b1d6516c00, ffff88b1d6516e00)

The problem is in the sess_dev release function we call
rnbd_destroy_sess_dev, and could free the sess_dev already, but we still
set the keep_id in rnbd_srv_sess_dev_force_close, which lead to use
after free.

To fix it, move the keep_id before the sysfs removal, and cache the
rnbd_srv_session for lock accessing,

Fixes: 7869980 ("block/rnbd-srv: close a mapped device from server side.")
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
dbaluta referenced this pull request in dbaluta/linux Feb 3, 2021
Since dynamically allocate sglist is used for rnbd_iu, we can't free sg
table after send_usr_msg since the callback function (cqe.done) could
still access the sglist.

Otherwise KASAN reports UAF issue:

[ 4856.600257] BUG: KASAN: use-after-free in dma_direct_unmap_sg+0x53/0x290
[ 4856.600772] Read of size 4 at addr ffff888206af3a98 by task swapper/1/0

[ 4856.601729] CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: G        W         5.10.0-pserver #5.10.0-1+feature+linux+next+20201214.1025+0910d71
[ 4856.601748] Hardware name: Supermicro Super Server/X11DDW-L, BIOS 3.3 02/21/2020
[ 4856.601766] Call Trace:
[ 4856.601785]  <IRQ>
[ 4856.601822]  dump_stack+0x99/0xcb
[ 4856.601856]  ? dma_direct_unmap_sg+0x53/0x290
[ 4856.601888]  print_address_description.constprop.7+0x1e/0x230
[ 4856.601913]  ? freeze_kernel_threads+0x73/0x73
[ 4856.601965]  ? mark_held_locks+0x29/0xa0
[ 4856.602019]  ? dma_direct_unmap_sg+0x53/0x290
[ 4856.602039]  ? dma_direct_unmap_sg+0x53/0x290
[ 4856.602079]  kasan_report.cold.9+0x37/0x7c
[ 4856.602188]  ? mlx5_ib_post_recv+0x430/0x520 [mlx5_ib]
[ 4856.602209]  ? dma_direct_unmap_sg+0x53/0x290
[ 4856.602256]  dma_direct_unmap_sg+0x53/0x290
[ 4856.602366]  complete_rdma_req+0x188/0x4b0 [rtrs_client]
[ 4856.602451]  ? rtrs_clt_close+0x80/0x80 [rtrs_client]
[ 4856.602535]  ? mlx5_ib_poll_cq+0x48b/0x16e0 [mlx5_ib]
[ 4856.602589]  ? radix_tree_insert+0x3a0/0x3a0
[ 4856.602610]  ? do_raw_spin_lock+0x119/0x1d0
[ 4856.602647]  ? rwlock_bug.part.1+0x60/0x60
[ 4856.602740]  rtrs_clt_rdma_done+0x3f7/0x670 [rtrs_client]
[ 4856.602804]  ? rtrs_clt_rdma_cm_handler+0xda0/0xda0 [rtrs_client]
[ 4856.602857]  ? check_flags.part.31+0x6c/0x1f0
[ 4856.602927]  ? rcu_read_lock_sched_held+0xaf/0xe0
[ 4856.602963]  ? rcu_read_lock_bh_held+0xc0/0xc0
[ 4856.603137]  __ib_process_cq+0x10a/0x350 [ib_core]
[ 4856.603309]  ib_poll_handler+0x41/0x1c0 [ib_core]
[ 4856.603358]  irq_poll_softirq+0xe6/0x280
[ 4856.603392]  ? lockdep_hardirqs_on_prepare+0x111/0x210
[ 4856.603446]  __do_softirq+0x10d/0x646
[ 4856.603540]  asm_call_irq_on_stack+0x12/0x20
[ 4856.603563]  </IRQ>

[ 4856.605096] Allocated by task 8914:
[ 4856.605510]  kasan_save_stack+0x19/0x40
[ 4856.605532]  __kasan_kmalloc.constprop.7+0xc1/0xd0
[ 4856.605552]  __kmalloc+0x155/0x320
[ 4856.605574]  __sg_alloc_table+0x155/0x1c0
[ 4856.605594]  sg_alloc_table+0x1f/0x50
[ 4856.605620]  send_msg_sess_info+0x119/0x2e0 [rnbd_client]
[ 4856.605646]  remap_devs+0x71/0x210 [rnbd_client]
[ 4856.605676]  init_sess+0xad8/0xe10 [rtrs_client]
[ 4856.605706]  rtrs_clt_reconnect_work+0xd6/0x170 [rtrs_client]
[ 4856.605728]  process_one_work+0x521/0xa90
[ 4856.605748]  worker_thread+0x65/0x5b0
[ 4856.605769]  kthread+0x1f2/0x210
[ 4856.605789]  ret_from_fork+0x22/0x30

[ 4856.606159] Freed by task 8914:
[ 4856.606559]  kasan_save_stack+0x19/0x40
[ 4856.606580]  kasan_set_track+0x1c/0x30
[ 4856.606601]  kasan_set_free_info+0x1b/0x30
[ 4856.606622]  __kasan_slab_free+0x108/0x150
[ 4856.606642]  slab_free_freelist_hook+0x64/0x190
[ 4856.606661]  kfree+0xe2/0x650
[ 4856.606681]  __sg_free_table+0xa4/0x100
[ 4856.606707]  send_msg_sess_info+0x1d6/0x2e0 [rnbd_client]
[ 4856.606733]  remap_devs+0x71/0x210 [rnbd_client]
[ 4856.606763]  init_sess+0xad8/0xe10 [rtrs_client]
[ 4856.606792]  rtrs_clt_reconnect_work+0xd6/0x170 [rtrs_client]
[ 4856.606813]  process_one_work+0x521/0xa90
[ 4856.606833]  worker_thread+0x65/0x5b0
[ 4856.606853]  kthread+0x1f2/0x210
[ 4856.606872]  ret_from_fork+0x22/0x30

The solution is to free iu's sgtable after the iu is not used anymore.
And also move sg_alloc_table into rnbd_get_iu accordingly.

Fixes: 5a1328d ("block/rnbd-clt: Dynamically allocate sglist for rnbd_iu")
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
dbaluta referenced this pull request in dbaluta/linux Feb 3, 2021
We had kernel panic, it is caused by unload module and last
close confirmation.

call trace:
[1196029.743127]  free_sess+0x15/0x50 [rtrs_client]
[1196029.743128]  rtrs_clt_close+0x4c/0x70 [rtrs_client]
[1196029.743129]  ? rnbd_clt_unmap_device+0x1b0/0x1b0 [rnbd_client]
[1196029.743130]  close_rtrs+0x25/0x50 [rnbd_client]
[1196029.743131]  rnbd_client_exit+0x93/0xb99 [rnbd_client]
[1196029.743132]  __x64_sys_delete_module+0x190/0x260

And in the crashdump confirmation kworker is also running.
PID: 6943   TASK: ffff9e2ac8098000  CPU: 4   COMMAND: "kworker/4:2"
 #0 [ffffb206cf337c30] __schedule at ffffffff9f93f891
 #1 [ffffb206cf337cc8] schedule at ffffffff9f93fe98
 #2 [ffffb206cf337cd0] schedule_timeout at ffffffff9f943938
 #3 [ffffb206cf337d50] wait_for_completion at ffffffff9f9410a7
 #4 [ffffb206cf337da0] __flush_work at ffffffff9f08ce0e
 #5 [ffffb206cf337e20] rtrs_clt_close_conns at ffffffffc0d5f668 [rtrs_client]
 #6 [ffffb206cf337e48] rtrs_clt_close at ffffffffc0d5f801 [rtrs_client]
 linux-kernel-labs#7 [ffffb206cf337e68] close_rtrs at ffffffffc0d26255 [rnbd_client]
 linux-kernel-labs#8 [ffffb206cf337e78] free_sess at ffffffffc0d262ad [rnbd_client]
 linux-kernel-labs#9 [ffffb206cf337e88] rnbd_clt_put_dev at ffffffffc0d266a7 [rnbd_client]

The problem is both code path try to close same session, which lead to
panic.

To fix it, just skip the sess if the refcount already drop to 0.

Fixes: f7a7a5c ("block/rnbd: client: main functionality")
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Gioh Kim <gi-oh.kim@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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