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<title>user/sven/linux.git/include, branch v5.9.12</title>
<subtitle>Linux Kernel
</subtitle>
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<updated>2020-12-02T07:51:56Z</updated>
<entry>
<title>bonding: wait for sysfs kobject destruction before freeing struct slave</title>
<updated>2020-12-02T07:51:56Z</updated>
<author>
<name>Jamie Iles</name>
<email>jamie@nuviainc.com</email>
</author>
<published>2020-11-20T14:28:27Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=58a1a33b365e0f0b46f33b978e68375662980ecf'/>
<id>urn:sha1:58a1a33b365e0f0b46f33b978e68375662980ecf</id>
<content type='text'>
[ Upstream commit b9ad3e9f5a7a760ab068e33e1f18d240ba32ce92 ]

syzkaller found that with CONFIG_DEBUG_KOBJECT_RELEASE=y, releasing a
struct slave device could result in the following splat:

  kobject: 'bonding_slave' (00000000cecdd4fe): kobject_release, parent 0000000074ceb2b2 (delayed 1000)
  bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
  ------------[ cut here ]------------
  ODEBUG: free active (active state 0) object type: timer_list hint: workqueue_select_cpu_near kernel/workqueue.c:1549 [inline]
  ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x98 kernel/workqueue.c:1600
  WARNING: CPU: 1 PID: 842 at lib/debugobjects.c:485 debug_print_object+0x180/0x240 lib/debugobjects.c:485
  Kernel panic - not syncing: panic_on_warn set ...
  CPU: 1 PID: 842 Comm: kworker/u4:4 Tainted: G S                5.9.0-rc8+ #96
  Hardware name: linux,dummy-virt (DT)
  Workqueue: netns cleanup_net
  Call trace:
   dump_backtrace+0x0/0x4d8 include/linux/bitmap.h:239
   show_stack+0x34/0x48 arch/arm64/kernel/traps.c:142
   __dump_stack lib/dump_stack.c:77 [inline]
   dump_stack+0x174/0x1f8 lib/dump_stack.c:118
   panic+0x360/0x7a0 kernel/panic.c:231
   __warn+0x244/0x2ec kernel/panic.c:600
   report_bug+0x240/0x398 lib/bug.c:198
   bug_handler+0x50/0xc0 arch/arm64/kernel/traps.c:974
   call_break_hook+0x160/0x1d8 arch/arm64/kernel/debug-monitors.c:322
   brk_handler+0x30/0xc0 arch/arm64/kernel/debug-monitors.c:329
   do_debug_exception+0x184/0x340 arch/arm64/mm/fault.c:864
   el1_dbg+0x48/0xb0 arch/arm64/kernel/entry-common.c:65
   el1_sync_handler+0x170/0x1c8 arch/arm64/kernel/entry-common.c:93
   el1_sync+0x80/0x100 arch/arm64/kernel/entry.S:594
   debug_print_object+0x180/0x240 lib/debugobjects.c:485
   __debug_check_no_obj_freed lib/debugobjects.c:967 [inline]
   debug_check_no_obj_freed+0x200/0x430 lib/debugobjects.c:998
   slab_free_hook mm/slub.c:1536 [inline]
   slab_free_freelist_hook+0x190/0x210 mm/slub.c:1577
   slab_free mm/slub.c:3138 [inline]
   kfree+0x13c/0x460 mm/slub.c:4119
   bond_free_slave+0x8c/0xf8 drivers/net/bonding/bond_main.c:1492
   __bond_release_one+0xe0c/0xec8 drivers/net/bonding/bond_main.c:2190
   bond_slave_netdev_event drivers/net/bonding/bond_main.c:3309 [inline]
   bond_netdev_event+0x8f0/0xa70 drivers/net/bonding/bond_main.c:3420
   notifier_call_chain+0xf0/0x200 kernel/notifier.c:83
   __raw_notifier_call_chain kernel/notifier.c:361 [inline]
   raw_notifier_call_chain+0x44/0x58 kernel/notifier.c:368
   call_netdevice_notifiers_info+0xbc/0x150 net/core/dev.c:2033
   call_netdevice_notifiers_extack net/core/dev.c:2045 [inline]
   call_netdevice_notifiers net/core/dev.c:2059 [inline]
   rollback_registered_many+0x6a4/0xec0 net/core/dev.c:9347
   unregister_netdevice_many.part.0+0x2c/0x1c0 net/core/dev.c:10509
   unregister_netdevice_many net/core/dev.c:10508 [inline]
   default_device_exit_batch+0x294/0x338 net/core/dev.c:10992
   ops_exit_list.isra.0+0xec/0x150 net/core/net_namespace.c:189
   cleanup_net+0x44c/0x888 net/core/net_namespace.c:603
   process_one_work+0x96c/0x18c0 kernel/workqueue.c:2269
   worker_thread+0x3f0/0xc30 kernel/workqueue.c:2415
   kthread+0x390/0x498 kernel/kthread.c:292
   ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:925

This is a potential use-after-free if the sysfs nodes are being accessed
whilst removing the struct slave, so wait for the object destruction to
complete before freeing the struct slave itself.

Fixes: 07699f9a7c8d ("bonding: add sysfs /slave dir for bond slave devices.")
Fixes: a068aab42258 ("bonding: Fix reference count leak in bond_sysfs_slave_add.")
Cc: Qiushi Wu &lt;wu000273@umn.edu&gt;
Cc: Jay Vosburgh &lt;j.vosburgh@gmail.com&gt;
Cc: Veaceslav Falico &lt;vfalico@gmail.com&gt;
Cc: Andy Gospodarek &lt;andy@greyhouse.net&gt;
Signed-off-by: Jamie Iles &lt;jamie@nuviainc.com&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Link: https://lore.kernel.org/r/20201120142827.879226-1-jamie@nuviainc.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>arch: pgtable: define MAX_POSSIBLE_PHYSMEM_BITS where needed</title>
<updated>2020-12-02T07:51:54Z</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2020-11-11T16:52:58Z</published>
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<id>urn:sha1:89aada63529fb0b175d7cb5175163f9f5ee66383</id>
<content type='text'>
[ Upstream commit cef397038167ac15d085914493d6c86385773709 ]

Stefan Agner reported a bug when using zsram on 32-bit Arm machines
with RAM above the 4GB address boundary:

  Unable to handle kernel NULL pointer dereference at virtual address 00000000
  pgd = a27bd01c
  [00000000] *pgd=236a0003, *pmd=1ffa64003
  Internal error: Oops: 207 [#1] SMP ARM
  Modules linked in: mdio_bcm_unimac(+) brcmfmac cfg80211 brcmutil raspberrypi_hwmon hci_uart crc32_arm_ce bcm2711_thermal phy_generic genet
  CPU: 0 PID: 123 Comm: mkfs.ext4 Not tainted 5.9.6 #1
  Hardware name: BCM2711
  PC is at zs_map_object+0x94/0x338
  LR is at zram_bvec_rw.constprop.0+0x330/0xa64
  pc : [&lt;c0602b38&gt;]    lr : [&lt;c0bda6a0&gt;]    psr: 60000013
  sp : e376bbe0  ip : 00000000  fp : c1e2921c
  r10: 00000002  r9 : c1dda730  r8 : 00000000
  r7 : e8ff7a00  r6 : 00000000  r5 : 02f9ffa0  r4 : e3710000
  r3 : 000fdffe  r2 : c1e0ce80  r1 : ebf979a0  r0 : 00000000
  Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
  Control: 30c5383d  Table: 235c2a80  DAC: fffffffd
  Process mkfs.ext4 (pid: 123, stack limit = 0x495a22e6)
  Stack: (0xe376bbe0 to 0xe376c000)

As it turns out, zsram needs to know the maximum memory size, which
is defined in MAX_PHYSMEM_BITS when CONFIG_SPARSEMEM is set, or in
MAX_POSSIBLE_PHYSMEM_BITS on the x86 architecture.

The same problem will be hit on all 32-bit architectures that have a
physical address space larger than 4GB and happen to not enable sparsemem
and include asm/sparsemem.h from asm/pgtable.h.

After the initial discussion, I suggested just always defining
MAX_POSSIBLE_PHYSMEM_BITS whenever CONFIG_PHYS_ADDR_T_64BIT is
set, or provoking a build error otherwise. This addresses all
configurations that can currently have this runtime bug, but
leaves all other configurations unchanged.

I looked up the possible number of bits in source code and
datasheets, here is what I found:

 - on ARC, CONFIG_ARC_HAS_PAE40 controls whether 32 or 40 bits are used
 - on ARM, CONFIG_LPAE enables 40 bit addressing, without it we never
   support more than 32 bits, even though supersections in theory allow
   up to 40 bits as well.
 - on MIPS, some MIPS32r1 or later chips support 36 bits, and MIPS32r5
   XPA supports up to 60 bits in theory, but 40 bits are more than
   anyone will ever ship
 - On PowerPC, there are three different implementations of 36 bit
   addressing, but 32-bit is used without CONFIG_PTE_64BIT
 - On RISC-V, the normal page table format can support 34 bit
   addressing. There is no highmem support on RISC-V, so anything
   above 2GB is unused, but it might be useful to eventually support
   CONFIG_ZRAM for high pages.

Fixes: 61989a80fb3a ("staging: zsmalloc: zsmalloc memory allocation library")
Fixes: 02390b87a945 ("mm/zsmalloc: Prepare to variable MAX_PHYSMEM_BITS")
Acked-by: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Reviewed-by: Stefan Agner &lt;stefan@agner.ch&gt;
Tested-by: Stefan Agner &lt;stefan@agner.ch&gt;
Acked-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Link: https://lore.kernel.org/linux-mm/bdfa44bf1c570b05d6c70898e2bbb0acf234ecdf.1604762181.git.stefan@agner.ch/
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>bus: ti-sysc: Fix reset status check for modules with quirks</title>
<updated>2020-12-02T07:51:52Z</updated>
<author>
<name>Tony Lindgren</name>
<email>tony@atomide.com</email>
</author>
<published>2020-10-26T08:08:47Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=e79c3d983c3e81474c0a718908224e60749d5c42'/>
<id>urn:sha1:e79c3d983c3e81474c0a718908224e60749d5c42</id>
<content type='text'>
[ Upstream commit e275d2109cdaea8b4554b9eb8a828bdb8f8ba068 ]

Commit d46f9fbec719 ("bus: ti-sysc: Use optional clocks on for enable and
wait for softreset bit") started showing a "OCP softreset timed out"
warning on enable if the interconnect target module is not out of reset.
This caused the warning to be often triggered for i2c and hdq while the
devices are working properly.

Turns out that some interconnect target modules seem to have an unusable
reset status bits unless the module specific reset quirks are activated.

Let's just skip the reset status check for those modules as we only want
to activate the reset quirks when doing a reset, and not on enable. This
way we don't see the bogus "OCP softreset timed out" warnings during boot.

Fixes: d46f9fbec719 ("bus: ti-sysc: Use optional clocks on for enable and wait for softreset bit")
Signed-off-by: Tony Lindgren &lt;tony@atomide.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>scsi: libiscsi: Fix NOP race condition</title>
<updated>2020-12-02T07:51:51Z</updated>
<author>
<name>Lee Duncan</name>
<email>lduncan@suse.com</email>
</author>
<published>2020-11-06T19:33:17Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=464eade52a6fde5febbd57e0f180e5aa05abb45a'/>
<id>urn:sha1:464eade52a6fde5febbd57e0f180e5aa05abb45a</id>
<content type='text'>
[ Upstream commit fe0a8a95e7134d0b44cd407bc0085b9ba8d8fe31 ]

iSCSI NOPs are sometimes "lost", mistakenly sent to the user-land iscsid
daemon instead of handled in the kernel, as they should be, resulting in a
message from the daemon like:

  iscsid: Got nop in, but kernel supports nop handling.

This can occur because of the new forward- and back-locks, and the fact
that an iSCSI NOP response can occur before processing of the NOP send is
complete. This can result in "conn-&gt;ping_task" being NULL in
iscsi_nop_out_rsp(), when the pointer is actually in the process of being
set.

To work around this, we add a new state to the "ping_task" pointer. In
addition to NULL (not assigned) and a pointer (assigned), we add the state
"being set", which is signaled with an INVALID pointer (using "-1").

Link: https://lore.kernel.org/r/20201106193317.16993-1-leeman.duncan@gmail.com
Reviewed-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Signed-off-by: Lee Duncan &lt;lduncan@suse.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>kunit: fix display of failed expectations for strings</title>
<updated>2020-12-02T07:51:49Z</updated>
<author>
<name>Daniel Latypov</name>
<email>dlatypov@google.com</email>
</author>
<published>2020-11-02T23:23:04Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=06b0f7e8c944eff7fcc9c52ffde97f12c4d15e7c'/>
<id>urn:sha1:06b0f7e8c944eff7fcc9c52ffde97f12c4d15e7c</id>
<content type='text'>
[ Upstream commit 3084db0e0d5076cd48408274ab0911cd3ccdae88 ]

Currently the following expectation
  KUNIT_EXPECT_STREQ(test, "hi", "bye");
will produce:
  Expected "hi" == "bye", but
      "hi" == 1625079497
      "bye" == 1625079500

After this patch:
  Expected "hi" == "bye", but
      "hi" == hi
      "bye" == bye

KUNIT_INIT_BINARY_STR_ASSERT_STRUCT() was written but just mistakenly
not actually used by KUNIT_EXPECT_STREQ() and friends.

Signed-off-by: Daniel Latypov &lt;dlatypov@google.com&gt;
Reviewed-by: Brendan Higgins &lt;brendanhiggins@google.com&gt;
Tested-by: Brendan Higgins &lt;brendanhiggins@google.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>trace: fix potenial dangerous pointer</title>
<updated>2020-12-02T07:51:47Z</updated>
<author>
<name>Hui Su</name>
<email>sh_def@163.com</email>
</author>
<published>2020-11-24T16:52:05Z</published>
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<id>urn:sha1:19d2c29ddead3869e94015ee283aad042a10d2f1</id>
<content type='text'>
commit fdeb17c70c9ecae655378761accf5a26a55a33cf upstream.

The bdi_dev_name() returns a char [64], and
the __entry-&gt;name is a char [32].

It maybe dangerous to TP_printk("%s", __entry-&gt;name)
after the strncpy().

CC: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201124165205.GA23937@rlk
Acked-by: Steven Rostedt (VMware) &lt;rostedt@goodmis.org&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Hui Su &lt;sh_def@163.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>firmware: xilinx: Use hash-table for api feature check</title>
<updated>2020-12-02T07:51:46Z</updated>
<author>
<name>Amit Sunil Dhamne</name>
<email>amit.sunil.dhamne@xilinx.com</email>
</author>
<published>2020-11-24T05:52:41Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=a38a99930883fb1e24f2a34b78a05a6598e86150'/>
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<content type='text'>
commit acfdd18591eaac25446e976a0c0d190f8b3dbfb1 upstream.

Currently array of fix length PM_API_MAX is used to cache
the pm_api version (valid or invalid). However ATF based
PM APIs values are much higher then PM_API_MAX.
So to include ATF based PM APIs also, use hash-table to
store the pm_api version status.

Signed-off-by: Amit Sunil Dhamne &lt;amit.sunil.dhamne@xilinx.com&gt;
Reported-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Ravi Patel &lt;ravi.patel@xilinx.com&gt;
Signed-off-by: Rajan Vaja &lt;rajan.vaja@xilinx.com&gt;
Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Tested-by: Michal Simek &lt;michal.simek@xilinx.com&gt;
Fixes: f3217d6f2f7a ("firmware: xilinx: fix out-of-bounds access")
Cc: stable &lt;stable@vger.kernel.org&gt;
Link: https://lore.kernel.org/r/1606197161-25976-1-git-send-email-rajan.vaja@xilinx.com
Signed-off-by: Michal Simek &lt;michal.simek@xilinx.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>mm: fix readahead_page_batch for retry entries</title>
<updated>2020-11-24T12:39:15Z</updated>
<author>
<name>Matthew Wilcox (Oracle)</name>
<email>willy@infradead.org</email>
</author>
<published>2020-11-22T06:17:08Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=9906d7a4839606307ca6bf072fd9a9d17f5daeac'/>
<id>urn:sha1:9906d7a4839606307ca6bf072fd9a9d17f5daeac</id>
<content type='text'>
commit 4349a83a3190c1d4414371161b0f4a4c3ccd3f9d upstream.

Both btrfs and fuse have reported faults caused by seeing a retry entry
instead of the page they were looking for.  This was caused by a missing
check in the iterator.

As can be seen in the below panic log, the accessing 0x402 causes a
panic.  In the xarray.h, 0x402 means RETRY_ENTRY.

  BUG: kernel NULL pointer dereference, address: 0000000000000402
  CPU: 14 PID: 306003 Comm: as Not tainted 5.9.0-1-amd64 #1 Debian 5.9.1-1
  Hardware name: Lenovo ThinkSystem SR665/7D2VCTO1WW, BIOS D8E106Q-1.01 05/30/2020
  RIP: 0010:fuse_readahead+0x152/0x470 [fuse]
  Code: 41 8b 57 18 4c 8d 54 10 ff 4c 89 d6 48 8d 7c 24 10 e8 d2 e3 28 f9 48 85 c0 0f 84 fe 00 00 00 44 89 f2 49 89 04 d4 44 8d 72 01 &lt;48&gt; 8b 10 41 8b 4f 1c 48 c1 ea 10 83 e2 01 80 fa 01 19 d2 81 e2 01
  RSP: 0018:ffffad99ceaebc50 EFLAGS: 00010246
  RAX: 0000000000000402 RBX: 0000000000000001 RCX: 0000000000000002
  RDX: 0000000000000000 RSI: ffff94c5af90bd98 RDI: ffffad99ceaebc60
  RBP: ffff94ddc1749a00 R08: 0000000000000402 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000100 R12: ffff94de6c429ce0
  R13: ffff94de6c4d3700 R14: 0000000000000001 R15: ffffad99ceaebd68
  FS:  00007f228c5c7040(0000) GS:ffff94de8ed80000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000402 CR3: 0000001dbd9b4000 CR4: 0000000000350ee0
  Call Trace:
    read_pages+0x83/0x270
    page_cache_readahead_unbounded+0x197/0x230
    generic_file_buffered_read+0x57a/0xa20
    new_sync_read+0x112/0x1a0
    vfs_read+0xf8/0x180
    ksys_read+0x5f/0xe0
    do_syscall_64+0x33/0x80
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 042124cc64c3 ("mm: add new readahead_control API")
Reported-by: David Sterba &lt;dsterba@suse.com&gt;
Reported-by: Wonhyuk Yang &lt;vvghjk1234@gmail.com&gt;
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Link: https://lkml.kernel.org/r/20201103142852.8543-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20201103124349.16722-1-vvghjk1234@gmail.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>spi: Introduce device-managed SPI controller allocation</title>
<updated>2020-11-24T12:39:11Z</updated>
<author>
<name>Lukas Wunner</name>
<email>lukas@wunner.de</email>
</author>
<published>2020-11-11T19:07:10Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=bd1a5b2307279029faaddbecf2f2ac25eaef8dc6'/>
<id>urn:sha1:bd1a5b2307279029faaddbecf2f2ac25eaef8dc6</id>
<content type='text'>
commit 5e844cc37a5cbaa460e68f9a989d321d63088a89 upstream.

SPI driver probing currently comprises two steps, whereas removal
comprises only one step:

    spi_alloc_master()
    spi_register_controller()

    spi_unregister_controller()

That's because spi_unregister_controller() calls device_unregister()
instead of device_del(), thereby releasing the reference on the
spi_controller which was obtained by spi_alloc_master().

An SPI driver's private data is contained in the same memory allocation
as the spi_controller struct.  Thus, once spi_unregister_controller()
has been called, the private data is inaccessible.  But some drivers
need to access it after spi_unregister_controller() to perform further
teardown steps.

Introduce devm_spi_alloc_master() and devm_spi_alloc_slave(), which
release a reference on the spi_controller struct only after the driver
has unbound, thereby keeping the memory allocation accessible.  Change
spi_unregister_controller() to not release a reference if the
spi_controller was allocated by one of these new devm functions.

The present commit is small enough to be backportable to stable.
It allows fixing drivers which use the private data in their -&gt;remove()
hook after it's been freed.  It also allows fixing drivers which neglect
to release a reference on the spi_controller in the probe error path.

Long-term, most SPI drivers shall be moved over to the devm functions
introduced herein.  The few that can't shall be changed in a treewide
commit to explicitly release the last reference on the controller.
That commit shall amend spi_unregister_controller() to no longer release
a reference, thereby completing the migration.

As a result, the behaviour will be less surprising and more consistent
with subsystems such as IIO, which also includes the private data in the
allocation of the generic iio_dev struct, but calls device_del() in
iio_device_unregister().

Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Link: https://lore.kernel.org/r/272bae2ef08abd21388c98e23729886663d19192.1605121038.git.lukas@wunner.de
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>sched: Fix data-race in wakeup</title>
<updated>2020-11-24T12:39:06Z</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2020-11-17T08:08:41Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=09b5b608f461cbd4dca250fc480e0f7bef6a140e'/>
<id>urn:sha1:09b5b608f461cbd4dca250fc480e0f7bef6a140e</id>
<content type='text'>
[ Upstream commit f97bb5272d9e95d400d6c8643ebb146b3e3e7842 ]

Mel reported that on some ARM64 platforms loadavg goes bananas and
Will tracked it down to the following race:

  CPU0					CPU1

  schedule()
    prev-&gt;sched_contributes_to_load = X;
    deactivate_task(prev);

					try_to_wake_up()
					  if (p-&gt;on_rq &amp;&amp;) // false
					  if (smp_load_acquire(&amp;p-&gt;on_cpu) &amp;&amp; // true
					      ttwu_queue_wakelist())
					        p-&gt;sched_remote_wakeup = Y;

    smp_store_release(prev-&gt;on_cpu, 0);

where both p-&gt;sched_contributes_to_load and p-&gt;sched_remote_wakeup are
in the same word, and thus the stores X and Y race (and can clobber
one another's data).

Whereas prior to commit c6e7bd7afaeb ("sched/core: Optimize ttwu()
spinning on p-&gt;on_cpu") the p-&gt;on_cpu handoff serialized access to
p-&gt;sched_remote_wakeup (just as it still does with
p-&gt;sched_contributes_to_load) that commit broke that by calling
ttwu_queue_wakelist() with p-&gt;on_cpu != 0.

However, due to

  p-&gt;XXX = X			ttwu()
  schedule()			  if (p-&gt;on_rq &amp;&amp; ...) // false
    smp_mb__after_spinlock()	  if (smp_load_acquire(&amp;p-&gt;on_cpu) &amp;&amp;
    deactivate_task()		      ttwu_queue_wakelist())
      p-&gt;on_rq = 0;		        p-&gt;sched_remote_wakeup = Y;

We can be sure any 'current' store is complete and 'current' is
guaranteed asleep. Therefore we can move p-&gt;sched_remote_wakeup into
the current flags word.

Note: while the observed failure was loadavg accounting gone wrong due
to ttwu() cobbering p-&gt;sched_contributes_to_load, the reverse problem
is also possible where schedule() clobbers p-&gt;sched_remote_wakeup,
this could result in enqueue_entity() wrecking -&gt;vruntime and causing
scheduling artifacts.

Fixes: c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p-&gt;on_cpu")
Reported-by: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Debugged-by: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://lkml.kernel.org/r/20201117083016.GK3121392@hirez.programming.kicks-ass.net
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
</feed>
