cr=0 is supposed to be an optimization to save CPU cycles, but if
buddy data (in memory) is not initialized then all this makes no sense
as we have to do sync IO taking a lot of cycles.  Also, at cr=0
mballoc doesn't choose any available chunk.  cr=1 also skips groups
using heuristic based on avg. fragment size.  It's more useful to skip
such groups and switch to cr=2 where groups will be scanned for
available chunks.  However, we always read the first block group in a
flex_bg so metadata blocks will get read into the first flex_bg if
possible.

Using sparse image and dm-slow virtual device of 120TB was
simulated, then the image was formatted and filled using debugfs to
mark ~85% of available space as busy.  mount process w/o the patch
couldn't complete in half an hour (according to vmstat it would take
~10-11 hours).  With the patch applied mount took ~20 seconds.

Lustre-bug-id: https://jira.whamcloud.com/browse/LU-12988Signed-off-by: Alex Zhuravlev <azhuravlev@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>

This should significantly improve bitmap loading, especially for flex
groups as it tries to load all bitmaps within a flex.group instead of
one by one synchronously.

Prefetching is done in 8 * flex_bg groups, so it should be 8
read-ahead reads for a single allocating thread. At the end of
allocation the thread waits for read-ahead completion and initializes
buddy information so that read-aheads are not lost in case of memory
pressure.

At cr=0 the number of prefetching IOs is limited per allocation
context to prevent a situation when mballoc loads thousands of bitmaps
looking for a perfect group and ignoring groups with good chunks.

Together with the patch "ext4: limit scanning of uninitialized groups"
the mount time (which includes few tiny allocations) of a 1PB
filesystem is reduced significantly:

               0% full    50%-full unpatched    patched
  mount time       33s                9279s       563s

[ Restructured by tytso; removed the state flags in the allocation
  context, so it can be used to lazily prefetch the allocation bitmaps
  immediately after the file system is mounted.  Skip prefetching
  block groups which are uninitialized.  Finally pass in the
  REQ_RAHEAD flag to the block layer while prefetching. ]
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Ext4 uses blkdev_get_by_dev() to get the block_device for journal device
which does check to see if the read-only block device was opened
read-only.

As a result ext4 will hapily proceed mounting the file system with
external journal on read-only device. This is bad as we would not be
able to use the journal leading to errors later on.

Instead of simply failing to mount file system in this case, treat it in
a similar way we treat internal journal on read-only device. Allow to
mount with -o noload in read-only mode.

This can be reproduced easily like this:

mke2fs -F -O journal_dev $JOURNAL_DEV 100M
mkfs.$FSTYPE -F -J device=$JOURNAL_DEV $FS_DEV
blockdev --setro $JOURNAL_DEV
mount $FS_DEV $MNT
touch $MNT/file
umount $MNT

leading to error like this

[ 1307.318713] ------------[ cut here ]------------
[ 1307.323362] generic_make_request: Trying to write to read-only block-device dm-2 (partno 0)
[ 1307.331741] WARNING: CPU: 36 PID: 3224 at block/blk-core.c:855 generic_make_request_checks+0x2c3/0x580
[ 1307.341041] Modules linked in: ext4 mbcache jbd2 rfkill intel_rapl_msr intel_rapl_common isst_if_commd
[ 1307.419445] CPU: 36 PID: 3224 Comm: jbd2/dm-2 Tainted: G        W I       5.8.0-rc5 #2
[ 1307.427359] Hardware name: Dell Inc. PowerEdge R740/01KPX8, BIOS 2.3.10 08/15/2019
[ 1307.434932] RIP: 0010:generic_make_request_checks+0x2c3/0x580
[ 1307.440676] Code: 94 03 00 00 48 89 df 48 8d 74 24 08 c6 05 cf 2b 18 01 01 e8 7f a4 ff ff 48 c7 c7 50e
[ 1307.459420] RSP: 0018:ffffc0d70eb5fb48 EFLAGS: 00010286
[ 1307.464646] RAX: 0000000000000000 RBX: ffff9b33b2978300 RCX: 0000000000000000
[ 1307.471780] RDX: ffff9b33e12a81e0 RSI: ffff9b33e1298000 RDI: ffff9b33e1298000
[ 1307.478913] RBP: ffff9b7b9679e0c0 R08: 0000000000000837 R09: 0000000000000024
[ 1307.486044] R10: 0000000000000000 R11: ffffc0d70eb5f9f0 R12: 0000000000000400
[ 1307.493177] R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
[ 1307.500308] FS:  0000000000000000(0000) GS:ffff9b33e1280000(0000) knlGS:0000000000000000
[ 1307.508396] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1307.514142] CR2: 000055eaf4109000 CR3: 0000003dee40a006 CR4: 00000000007606e0
[ 1307.521273] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1307.528407] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1307.535538] PKRU: 55555554
[ 1307.538250] Call Trace:
[ 1307.540708]  generic_make_request+0x30/0x340
[ 1307.544985]  submit_bio+0x43/0x190
[ 1307.548393]  ? bio_add_page+0x62/0x90
[ 1307.552068]  submit_bh_wbc+0x16a/0x190
[ 1307.555833]  jbd2_write_superblock+0xec/0x200 [jbd2]
[ 1307.560803]  jbd2_journal_update_sb_log_tail+0x65/0xc0 [jbd2]
[ 1307.566557]  jbd2_journal_commit_transaction+0x2ae/0x1860 [jbd2]
[ 1307.572566]  ? check_preempt_curr+0x7a/0x90
[ 1307.576756]  ? update_curr+0xe1/0x1d0
[ 1307.580421]  ? account_entity_dequeue+0x7b/0xb0
[ 1307.584955]  ? newidle_balance+0x231/0x3d0
[ 1307.589056]  ? __switch_to_asm+0x42/0x70
[ 1307.592986]  ? __switch_to_asm+0x36/0x70
[ 1307.596918]  ? lock_timer_base+0x67/0x80
[ 1307.600851]  kjournald2+0xbd/0x270 [jbd2]
[ 1307.604873]  ? finish_wait+0x80/0x80
[ 1307.608460]  ? commit_timeout+0x10/0x10 [jbd2]
[ 1307.612915]  kthread+0x114/0x130
[ 1307.616152]  ? kthread_park+0x80/0x80
[ 1307.619816]  ret_from_fork+0x22/0x30
[ 1307.623400] ---[ end trace 27490236265b1630 ]---
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20200717090605.2612-1-lczerner@redhat.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Fix spelling typos in ext4_mb_initialize_context.
Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/883b523c-58ec-7f38-0bb8-cd2ea4393684@gmail.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Don't define EXT4_IOC_* aliases to ioctls that already have a generic
FS_IOC_* name.  These aliases are unnecessary, and they make it unclear
which ioctls are ext4-specific and which are generic.

Exception: leave EXT4_IOC_GETVERSION_OLD and EXT4_IOC_SETVERSION_OLD
as-is for now, since renaming them to FS_IOC_GETVERSION and
FS_IOC_SETVERSION would probably make them more likely to be confused
with EXT4_IOC_GETVERSION and EXT4_IOC_SETVERSION which also exist.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200714230909.56349-1-ebiggers@kernel.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Define the EXT4_FL_USER_* constants by OR-ing together the appropriate
flags, rather than hard-coding a numeric value.  This makes it much
easier to see which flags are listed.

No change in the actual values.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200713031012.192440-1-ebiggers@kernel.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

A customer has reported a BUG_ON in ext4_clear_journal_err() hitting
during an LTP testing. Either this has been caused by a test setup
issue where the filesystem was being overwritten while LTP was mounting
it or the journal replay has overwritten the superblock with invalid
data. In either case it is preferable we don't take the machine down
with a BUG_ON. So handle the situation of unexpectedly missing
has_journal feature more gracefully. We issue warning and fail the mount
in the cases where the race window is narrow and the failed check is
most likely a programming error. In cases where fs corruption is more
likely, we do full ext4_error() handling before failing mount / remount.
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200710140759.18031-1-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Since commit 378f32ba ("ext4: introduce direct I/O write using iomap
infrastructure") we don't properly bail out of RWF_NOWAIT direct IO
write if underlying blocks are not allocated. Also
ext4_dio_write_checks() does not honor RWF_NOWAIT when re-acquiring
i_rwsem. Fix both issues.

Fixes: 378f32ba ("ext4: introduce direct I/O write using iomap infrastructure")
Cc: stable@kernel.org
Reported-by: Filipe Manana <fdmanana@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20200708153516.9507-1-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
  If not .svg:
    For each line:
      If doesn't contain `\bxmlns\b`:
        For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
          If both the HTTP and HTTPS versions
          return 200 OK and serve the same content:
            Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200706190339.20709-1-grandmaster@al2klimov.deSigned-off-by: Theodore Ts'o <tytso@mit.edu>

If dquot_initialize() return non-zero and trace of ext4_unlink_enter/exit
enabled then the matching-pair of trace_exit will lost in log.
Signed-off-by: Yi Zhuang <zhuangyi1@huawei.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20200629122621.129953-1-zhuangyi1@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

It should call trace exit in all return path for ext4_truncate.
Signed-off-by: zhengliang <zhengliang6@huawei.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20200701083027.45996-1-zhengliang6@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

jbd2_write_superblock() is under the buffer lock of journal superblock
before ending that superblock write, so add a missing unlock_buffer() in
in the error path before submitting buffer.

Fixes: 742b06b5 ("jbd2: check superblock mapped prior to committing")
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20200620061948.2049579-1-yi.zhang@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

If for any reason a directory passed to do_split() does not have enough
active entries to exceed half the size of the block, we can end up
iterating over all "count" entries without finding a split point.

In this case, count == move, and split will be zero, and we will
attempt a negative index into map[].

Guard against this by detecting this case, and falling back to
split-to-half-of-count instead; in this case we will still have
plenty of space (> half blocksize) in each split block.

Fixes: ef2b02d3 ("ext34: ensure do_split leaves enough free space in both blocks")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/f53e246b-647c-64bb-16ec-135383c70ad7@redhat.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Callers of __jbd2_journal_unfile_buffer() and
__jbd2_journal_refile_buffer() assume that the b_transaction is set. In
fact if it's not, we can end up with journal_head refcounting errors
leading to crash much later that might be very hard to track down. Add
asserts to make sure that is the case.

We also make sure that b_next_transaction is NULL in
__jbd2_journal_unfile_buffer() since the callers expect that as well and
we should not get into that stage in this state anyway, leading to
problems later on if we do.

Tested with fstests.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200617092549.6712-1-lczerner@redhat.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Fixed a few coding style issues in file.c
Signed-off-by: Dio Putra <dioput12@gmail.com>
Link: https://lore.kernel.org/r/239fcd8f-d33f-8621-9e82-0416dd3f9c94@gmail.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

The brelse() function tests whether its argument is NULL
and then returns immediately.
Thus remove the tests which are not needed around the shown calls.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/0d713702-072f-a89c-20ec-ca70aa83a432@web.deSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Fix spelling issues over the comments in the code.

requsted ==> requested
deterimined ==> determined
insde ==> inside
neet ==> need
somthing ==> something
Signed-off-by: Keyur Patel <iamkeyur96@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200611031947.165079-1-iamkeyur96@gmail.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Using a mutex for "print this warning only once" is so overdesigned as
to be actively offensive to my sensitive stomach.

Just use "pr_info_once()" that already does this, although in a
(harmlessly) racy manner that can in theory cause the message to be
printed twice if more than one CPU races on that "is this the first
time" test.

[ If somebody really cares about that harmless data race (which sounds
  very unlikely indeed), that person can trivially fix printk_once() by
  using a simple atomic access, preferably with an optimistic non-atomic
  test first before even bothering to treat the pointless "make sure it
  is _really_ just once" case.

  A mutex is most definitely never the right primitive to use for
  something like this. ]

Yes, this is a small and meaningless detail in a code path that hardly
matters.  But let's keep some code quality standards here, and not
accept outrageously bad code.

Link: https://lore.kernel.org/lkml/CAHk-=wgV9toS7GU3KmNpj8hCS9SeF+A0voHS8F275_mgLhL4Lw@mail.gmail.com/
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull x86 fixes from Thomas Gleixner:
 "A series of fixes for x86:

   - Reset MXCSR in kernel_fpu_begin() to prevent using a stale user
     space value.

   - Prevent writing MSR_TEST_CTRL on CPUs which are not explicitly
     whitelisted for split lock detection. Some CPUs which do not
     support it crash even when the MSR is written to 0 which is the
     default value.

   - Fix the XEN PV fallout of the entry code rework

   - Fix the 32bit fallout of the entry code rework

   - Add more selftests to ensure that these entry problems don't come
     back.

   - Disable 16 bit segments on XEN PV. It's not supported because XEN
     PV does not implement ESPFIX64"

* tag 'x86-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ldt: Disable 16-bit segments on Xen PV
  x86/entry/32: Fix #MC and #DB wiring on x86_32
  x86/entry/xen: Route #DB correctly on Xen PV
  x86/entry, selftests: Further improve user entry sanity checks
  x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER
  selftests/x86: Consolidate and fix get/set_eflags() helpers
  selftests/x86/syscall_nt: Clear weird flags after each test
  selftests/x86/syscall_nt: Add more flag combinations
  x86/entry/64/compat: Fix Xen PV SYSENTER frame setup
  x86/entry: Move SYSENTER's regs->sp and regs->flags fixups into C
  x86/entry: Assert that syscalls are on the right stack
  x86/split_lock: Don't write MSR_TEST_CTRL on CPUs that aren't whitelisted
  x86/fpu: Reset MXCSR to default in kernel_fpu_begin()

Pull irq fixes from Thomas Gleixner:
 "A set of interrupt chip driver fixes:

   - Ensure the atomicity of affinity updates in the GIC driver

   - Don't try to sleep in atomic context when waiting for the GICv4.1
     to respond. Use polling instead.

   - Typo fixes in Kconfig and warnings"

* tag 'irq-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic: Atomically update affinity
  irqchip/riscv-intc: Fix a typo in a pr_warn()
  irqchip/gic-v4.1: Use readx_poll_timeout_atomic() to fix sleep in atomic
  irqchip/loongson-pci-msi: Fix a typo in Kconfig

Pull rcu fixlet from Thomas Gleixner:
 "A single fix for a printk format warning in RCU"

* tag 'core-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcuperf: Fix printk format warning

Merge tag 'kbuild-fixes-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes frin Masahiro Yamada:

 - fix various bugs in xconfig

 - fix some issues in cross-compilation using Clang

 - fix documentation

* tag 'kbuild-fixes-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  .gitignore: Do not track `defconfig` from `make savedefconfig`
  kbuild: make Clang build userprogs for target architecture
  kbuild: fix CONFIG_CC_CAN_LINK(_STATIC) for cross-compilation with Clang
  kconfig: qconf: parse newer types at debug info
  kconfig: qconf: navigate menus on hyperlinks
  kconfig: qconf: don't show goback button on splitMode
  kconfig: qconf: simplify the goBack() logic
  kconfig: qconf: re-implement setSelected()
  kconfig: qconf: make debug links work again
  kconfig: qconf: make search fully work again on split mode
  kconfig: qconf: cleanup includes
  docs: kbuild: fix ReST formatting
  gcc-plugins: fix gcc-plugins directory path in documentation

Pull SCSI fixes from James Bottomley:
 "Four small fixes in three drivers.

  The mptfusion one has actually caused user visible issues in certain
  kernel configurations"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: mptfusion: Don't use GFP_ATOMIC for larger DMA allocations
  scsi: libfc: Skip additional kref updating work event
  scsi: libfc: Handling of extra kref
  scsi: qla2xxx: Fix a condition in qla2x00_find_all_fabric_devs()

Pull block fixes from Jens Axboe:

 - NVMe fixes from Christoph:
    - Fix crash in multi-path disk add (Christoph)
    - Fix ignore of identify error (Sagi)

 - Fix a compiler complaint that a function should be static (Wei)

* tag 'block-5.8-2020-07-05' of git://git.kernel.dk/linux-block:
  block: make function __bio_integrity_free() static
  nvme: fix a crash in nvme_mpath_add_disk
  nvme: fix identify error status silent ignore

Pull io_uring fix from Jens Axboe:
 "Andres reported a regression with the fix that was merged earlier this
  week, where his setup of using signals to interrupt io_uring CQ waits
  no longer worked correctly.

  Fix this, and also limit our use of TWA_SIGNAL to the case where we
  need it, and continue using TWA_RESUME for task_work as before.

  Since the original is marked for 5.7 stable, let's flush this one out
  early"

* tag 'io_uring-5.8-2020-07-05' of git://git.kernel.dk/linux-block:
  io_uring: fix regression with always ignoring signals in io_cqring_wait()

Pull i2c fixes from Wolfram Sang:
 "The usual driver fixes and documentation updates"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: mlxcpld: check correct size of maximum RECV_LEN packet
  i2c: add Kconfig help text for slave mode
  i2c: slave-eeprom: update documentation
  i2c: eg20t: Load module automatically if ID matches
  i2c: designware: platdrv: Set class based on DMI
  i2c: algo-pca: Add 0x78 as SCL stuck low status for PCA9665

Pull MIPS fixes from Thomas Bogendoerfer:

 - fix for missing hazard barrier

 - DT fix for ingenic

 - DT fix of GPHY names for lantiq

 - fix usage of smp_processor_id() while preemption is enabled

* tag 'mips_fixes_5.8_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  MIPS: Do not use smp_processor_id() in preemptible code
  MIPS: Add missing EHB in mtc0 -> mfc0 sequence for DSPen
  MIPS: ingenic: gcw0: Fix HP detection GPIO.
  MIPS: lantiq: xway: sysctrl: fix the GPHY clock alias names

Use preempt_disable() to fix the following bug under CONFIG_DEBUG_PREEMPT.

[   21.915305] BUG: using smp_processor_id() in preemptible [00000000] code: qemu-system-mip/1056
[   21.923996] caller is do_ri+0x1d4/0x690
[   21.927921] CPU: 0 PID: 1056 Comm: qemu-system-mip Not tainted 5.8.0-rc2 #3
[   21.934913] Stack : 0000000000000001 ffffffff81370000 ffffffff8071cd60 a80f926d5ac95694
[   21.942984]         a80f926d5ac95694 0000000000000000 98000007f0043c88 ffffffff80f2fe40
[   21.951054]         0000000000000000 0000000000000000 0000000000000001 0000000000000000
[   21.959123]         ffffffff802d60cc 98000007f0043dd8 ffffffff81f4b1e8 ffffffff81f60000
[   21.967192]         ffffffff81f60000 ffffffff80fe0000 ffff000000000000 0000000000000000
[   21.975261]         fffffffff500cce1 0000000000000001 0000000000000002 0000000000000000
[   21.983331]         ffffffff80fe1a40 0000000000000006 ffffffff8077f940 0000000000000000
[   21.991401]         ffffffff81460000 98000007f0040000 98000007f0043c80 000000fffba8cf20
[   21.999471]         ffffffff8071cd60 0000000000000000 0000000000000000 0000000000000000
[   22.007541]         0000000000000000 0000000000000000 ffffffff80212ab4 a80f926d5ac95694
[   22.015610]         ...
[   22.018086] Call Trace:
[   22.020562] [<ffffffff80212ab4>] show_stack+0xa4/0x138
[   22.025732] [<ffffffff8071cd60>] dump_stack+0xf0/0x150
[   22.030903] [<ffffffff80c73f5c>] check_preemption_disabled+0xf4/0x100
[   22.037375] [<ffffffff80213b84>] do_ri+0x1d4/0x690
[   22.042198] [<ffffffff8020b828>] handle_ri_int+0x44/0x5c
[   24.359386] BUG: using smp_processor_id() in preemptible [00000000] code: qemu-system-mip/1072
[   24.368204] caller is do_ri+0x1a8/0x690
[   24.372169] CPU: 4 PID: 1072 Comm: qemu-system-mip Not tainted 5.8.0-rc2 #3
[   24.379170] Stack : 0000000000000001 ffffffff81370000 ffffffff8071cd60 a80f926d5ac95694
[   24.387246]         a80f926d5ac95694 0000000000000000 98001007ef06bc88 ffffffff80f2fe40
[   24.395318]         0000000000000000 0000000000000000 0000000000000001 0000000000000000
[   24.403389]         ffffffff802d60cc 98001007ef06bdd8 ffffffff81f4b818 ffffffff81f60000
[   24.411461]         ffffffff81f60000 ffffffff80fe0000 ffff000000000000 0000000000000000
[   24.419533]         fffffffff500cce1 0000000000000001 0000000000000002 0000000000000000
[   24.427603]         ffffffff80fe0000 0000000000000006 ffffffff8077f940 0000000000000020
[   24.435673]         ffffffff81460020 98001007ef068000 98001007ef06bc80 000000fffbbbb370
[   24.443745]         ffffffff8071cd60 0000000000000000 0000000000000000 0000000000000000
[   24.451816]         0000000000000000 0000000000000000 ffffffff80212ab4 a80f926d5ac95694
[   24.459887]         ...
[   24.462367] Call Trace:
[   24.464846] [<ffffffff80212ab4>] show_stack+0xa4/0x138
[   24.470029] [<ffffffff8071cd60>] dump_stack+0xf0/0x150
[   24.475208] [<ffffffff80c73f5c>] check_preemption_disabled+0xf4/0x100
[   24.481682] [<ffffffff80213b58>] do_ri+0x1a8/0x690
[   24.486509] [<ffffffff8020b828>] handle_ri_int+0x44/0x5c
Signed-off-by: Xingxing Su <suxingxing@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

This resolves the hazard between the mtc0 in the change_c0_status() and
the mfc0 in configure_exception_vector(). Without resolving this hazard
configure_exception_vector() could read an old value and would restore
this old value again. This would revert the changes change_c0_status()
did. I checked this by printing out the read_c0_status() at the end of
per_cpu_trap_init() and the ST0_MX is not set without this patch.

The hazard is documented in the MIPS Architecture Reference Manual Vol.
III: MIPS32/microMIPS32 Privileged Resource Architecture (MD00088), rev
6.03 table 8.1 which includes:

   Producer | Consumer | Hazard
  ----------|----------|----------------------------
   mtc0     | mfc0     | any coprocessor 0 register

I saw this hazard on an Atheros AR9344 rev 2 SoC with a MIPS 74Kc CPU.
There the change_c0_status() function would activate the DSPen by
setting ST0_MX in the c0_status register. This was reverted and then the
system got a DSP exception when the DSP registers were saved in
save_dsp() in the first process switch. The crash looks like this:

[    0.089999] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[    0.097796] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[    0.107070] Kernel panic - not syncing: Unexpected DSP exception
[    0.113470] Rebooting in 1 seconds..

We saw this problem in OpenWrt only on the MIPS 74Kc based Atheros SoCs,
not on the 24Kc based SoCs. We only saw it with kernel 5.4 not with
kernel 4.19, in addition we had to use GCC 8.4 or 9.X, with GCC 8.3 it
did not happen.

In the kernel I bisected this problem to commit 9012d011 ("compiler:
allow all arches to enable CONFIG_OPTIMIZE_INLINING"), but when this was
reverted it also happened after commit 172dcd93 ("MIPS: Always
allocate exception vector for MIPSr2+").

Commit 0b24cae4 ("MIPS: Add missing EHB in mtc0 -> mfc0 sequence.")
does similar changes to a different file. I am not sure if there are
more places affected by this problem.
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

Running `make savedefconfig` creates by default `defconfig`, which is,
currently, on git’s radar, for example, `git status` lists this file as
untracked.

So, add the file to `.gitignore`, so it’s ignored by git.
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Pull powerpc fixes from Michael Ellerman:
 "One fix for a regression in our pkey handling, which exhibits as
  PROT_EXEC mappings taking continuous page faults.

  Thanks to: Jan Stancek, Aneesh Kumar K.V"

* tag 'powerpc-5.8-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mm/pkeys: Make pkey access check work on execute_only_key

Pull arm64 fixes from Will Deacon:
 "Nothing earth-shattering, really - some CPU errata workarounds (one
  day they'll get it right, ha!) and a fix for a boot failure with very
  large kernel images where the alternative patching gets confused when
  patching relative branches using veneers.

   - Fix alternative patching for very large kernel images and modules

   - Hook up existing CPU errata workarounds for Qualcomm Kryo CPUs"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Add KRYO4XX silver CPU cores to erratum list 1530923 and 1024718
  arm64: Add KRYO4XX gold CPU cores to erratum list 1463225 and 1418040
  arm64: Add MIDR value for KRYO4XX gold CPU cores
  arm64/alternatives: use subsections for replacement sequences

When switching to TWA_SIGNAL for task_work notifications, we also made
any signal based condition in io_cqring_wait() return -ERESTARTSYS.
This breaks applications that rely on using signals to abort someone
waiting for events.

Check if we have a signal pending because of queued task_work, and
repeat the signal check once we've run the task_work. This provides a
reliable way of telling the two apart.

Additionally, only use TWA_SIGNAL if we are using an eventfd. If not,
we don't have the dependency situation described in the original commit,
and we can get by with just using TWA_RESUME like we previously did.

Fixes: ce593a6c ("io_uring: use signal based task_work running")
Cc: stable@vger.kernel.org # v5.7
Reported-by: Andres Freund <andres@anarazel.de>
Tested-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Xen PV doesn't implement ESPFIX64, so they don't work right.  Disable
them.  Also print a warning the first time anyone tries to use a
16-bit segment on a Xen PV guest that would otherwise allow it
to help people diagnose this change in behavior.

This gets us closer to having all x86 selftests pass on Xen PV.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/92b2975459dfe5929ecf34c3896ad920bd9e3f2d.1593795633.git.luto@kernel.org

DEFINE_IDTENTRY_MCE and DEFINE_IDTENTRY_DEBUG were wired up as non-RAW
on x86_32, but the code expected them to be RAW.

Get rid of all the macro indirection for them on 32-bit and just use
DECLARE_IDTENTRY_RAW and DEFINE_IDTENTRY_RAW directly.

Also add a warning to make sure that we only hit the _kernel paths
in kernel mode.
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9e90a7ee8e72fd757db6d92e1e5ff16339c1ecf9.1593795633.git.luto@kernel.org

On Xen PV, #DB doesn't use IST. It still needs to be correctly routed
depending on whether it came from user or kernel mode.

Get rid of DECLARE/DEFINE_IDTENTRY_XEN -- it was too hard to follow the
logic.  Instead, route #DB and NMI through DECLARE/DEFINE_IDTENTRY_RAW on
Xen, and do the right thing for #DB.  Also add more warnings to the
exc_debug* handlers to make this type of failure more obvious.

This fixes various forms of corruption that happen when usermode
triggers #DB on Xen PV.

Fixes: 4c0dcd83 ("x86/entry: Implement user mode C entry points for #DB and #MCE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/4163e733cce0b41658e252c6c6b3464f33fdff17.1593795633.git.luto@kernel.org

Chasing down a Xen bug caused me to realize that the new entry sanity
checks are still fairly weak.  Add some more checks.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/881de09e786ab93ce56ee4a2437ba2c308afe7a9.1593795633.git.luto@kernel.org

Move the clearing of the high bits of RAX after Xen PV joins the SYSENTER
path so that Xen PV doesn't skip it.

Arguably this code should be deleted instead, but that would belong in the
merge window.

Fixes: ffae641f ("x86/entry/64/compat: Fix Xen PV SYSENTER frame setup")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9d33b3f3216dcab008070f1c28b6091ae7199969.1593795633.git.luto@kernel.org

Pull xen fixes from Juergen Gross:
 "One small cleanup patch for ARM and two patches for the xenbus driver
  fixing latent problems (large stack allocations and bad return code
  settings)"

* tag 'for-linus-5.8b-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/xenbus: let xenbus_map_ring_valloc() return errno values only
  xen/xenbus: avoid large structs and arrays on the stack
  arm/xen: remove the unused macro GRANT_TABLE_PHYSADDR