Article 5S2X3 Prediction: How many reverts will 5.15.4 contain?

Prediction: How many reverts will 5.15.4 contain?

by
drumz
from LinuxQuestions.org on (#5S2X3)
We need a distraction!

Here's a fun guessing game. How many reverts (including partial reverts) will Linux kernel 5.15.4 contain? 5.15.3 contains 920 patches.

The revert doesn't specifically have to be a patch in 5.15.3 (that will be too hard for me to count).

By my count 5.15.3 itself contains 9 reverts (selected by searching for "revert" in the Changelog and subjectively deciding if the commit message indicates whether or not the patch is a full or partial revert):

Code:commit 3e1e7e4a6b54b9ed9a633a9faeb8f0dafd6dd7fb
Author: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Mon Jul 12 09:52:59 2021 -0400

SUNRPC: Partial revert of commit 6f9f17287e78

commit ea7a1019d8baf8503ecd6e3ec8436dec283569e6 upstream.

The premise of commit 6f9f17287e78 ("SUNRPC: Mitigate cond_resched() in
xprt_transmit()") was that cond_resched() is expensive and unnecessary
when there has been just a single send.
The point of cond_resched() is to ensure that tasks that should pre-empt
this one get a chance to do so when it is safe to do so. The code prior
to commit 6f9f17287e78 failed to take into account that it was keeping a
rpc_task pinned for longer than it needed to, and so rather than doing a
full revert, let's just move the cond_resched.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>Code:commit ac8ffb5d9dfbdb965f72732a0e214cfcdc8eb44c
Author: Coly Li <colyli@suse.de>
Date: Wed Nov 3 23:10:41 2021 +0800

bcache: Revert "bcache: use bvec_virt"

commit 2878feaed543c35f9dbbe6d8ce36fb67ac803eef upstream.

This reverts commit 2fd3e5efe791946be0957c8e1eed9560b541fe46.

The above commit replaces page_address(bv->bv_page) by bvec_virt(bv) to
avoid directly access to bv->bv_page, but in situation bv->bv_offset is
not zero and page_address(bv->bv_page) is not equal to bvec_virt(bv). In
such case a memory corruption may happen because memory in next page is
tainted by following line in do_btree_node_write(),
memcpy(bvec_virt(bv), addr, PAGE_SIZE);

This patch reverts the mentioned commit to avoid the memory corruption.

Fixes: 2fd3e5efe791 ("bcache: use bvec_virt")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org # 5.15
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211103151041.70516-1-colyli@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>Code:commit 97308cd5ce8edc466a2eed1bb31fd81a088ed54d
Author: Fabio Estevam <festevam@gmail.com>
Date: Wed Nov 3 21:11:12 2021 -0300

Revert "drm/imx: Annotate dma-fence critical section in commit path"

[ Upstream commit 14d9a37c952588930d7226953359fea3ab956d39 ]

This reverts commit f4b34faa08428d813fc3629f882c503487f94a12.

Since commit f4b34faa0842 ("drm/imx: Annotate dma-fence critical section in
commit path") the following possible circular dependency is detected:

[ 5.001811] ======================================================
[ 5.001817] WARNING: possible circular locking dependency detected
[ 5.001824] 5.14.9-01225-g45da36cc6fcc-dirty #1 Tainted: G W
[ 5.001833] ------------------------------------------------------
[ 5.001838] kworker/u8:0/7 is trying to acquire lock:
[ 5.001848] c1752080 (regulator_list_mutex){+.+.}-{3:3}, at: regulator_lock_dependent+0x40/0x294
[ 5.001903]
[ 5.001903] but task is already holding lock:
[ 5.001909] c176df78 (dma_fence_map){++++}-{0:0}, at: imx_drm_atomic_commit_tail+0x10/0x160
[ 5.001957]
[ 5.001957] which lock already depends on the new lock.
...

Revert it for now.

Tested on a imx6q-sabresd.

Fixes: f4b34faa0842 ("drm/imx: Annotate dma-fence critical section in commit path")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20211104001112.4035691-1-festevam@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>Code:commit cab693c0fe29a714e69afb8b472619d951941fc8
Author: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Mon Oct 4 15:44:16 2021 -0400

NFS: Fix deadlocks in nfs_scan_commit_list()

[ Upstream commit 64a93dbf25d3a1368bb58ddf0f61d0a92d7479e3 ]

Partially revert commit 2ce209c42c01 ("NFS: Wait for requests that are
locked on the commit list"), since it can lead to deadlocks between
commit requests and nfs_join_page_group().
For now we should assume that any locked requests on the commit list are
either about to be removed and committed by another task, or the writes
they describe are about to be retransmitted. In either case, we should
not need to worry.

Fixes: 2ce209c42c01 ("NFS: Wait for requests that are locked on the commit list")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>Code:commit bf736690bcbe39c328eef22e00314e38b3fa4475
Author: Hao Wu <hao.wu@rubrik.com>
Date: Wed Sep 8 02:26:06 2021 -0700

tpm: fix Atmel TPM crash caused by too frequent queries

[ Upstream commit 79ca6f74dae067681a779fd573c2eb59649989bc ]

The Atmel TPM 1.2 chips crash with error
`tpm_try_transmit: send(): error -62` since kernel 4.14.
It is observed from the kernel log after running `tpm_sealdata -z`.
The error thrown from the command is as follows
```
$ tpm_sealdata -z
Tspi_Key_LoadKey failed: 0x00001087 - layer=tddl,
code=0087 (135), I/O error
```

The issue was reproduced with the following Atmel TPM chip:
```
$ tpm_version
T0 TPM 1.2 Version Info:
Chip Version: 1.2.66.1
Spec Level: 2
Errata Revision: 3
TPM Vendor ID: ATML
TPM Version: 01010000
Manufacturer Info: 41544d4c
```

The root cause of the issue is due to the TPM calls to msleep()
were replaced with usleep_range() [1], which reduces
the actual timeout. Via experiments, it is observed that
the original msleep(5) actually sleeps for 15ms.
Because of a known timeout issue in Atmel TPM 1.2 chip,
the shorter timeout than 15ms can cause the error described above.

A few further changes in kernel 4.16 [2] and 4.18 [3, 4] further
reduced the timeout to less than 1ms. With experiments,
the problematic timeout in the latest kernel is the one
for `wait_for_tpm_stat`.

To fix it, the patch reverts the timeout of `wait_for_tpm_stat`
to 15ms for all Atmel TPM 1.2 chips, but leave it untouched
for Ateml TPM 2.0 chip, and chips from other vendors.
As explained above, the chosen 15ms timeout is
the actual timeout before this issue introduced,
thus the old value is used here.
Particularly, TPM_ATML_TIMEOUT_WAIT_STAT_MIN is set to 14700us,
TPM_ATML_TIMEOUT_WAIT_STAT_MIN is set to 15000us according to
the existing TPM_TIMEOUT_RANGE_US (300us).
The fixed has been tested in the system with the affected Atmel chip
with no issues observed after boot up.

References:
[1] 9f3fc7bcddcb tpm: replace msleep() with usleep_range() in TPM
1.2/2.0 generic drivers
[2] cf151a9a44d5 tpm: reduce tpm polling delay in tpm_tis_core
[3] 59f5a6b07f64 tpm: reduce poll sleep time in tpm_transmit()
[4] 424eaf910c32 tpm: reduce polling time to usecs for even finer
granularity

Fixes: 9f3fc7bcddcb ("tpm: replace msleep() with usleep_range() in TPM 1.2/2.0 generic drivers")
Link: https://patchwork.kernel.org/project/linux-integrity/patch/20200926223150.109645-1-hao.wu@rubrik.com/
Signed-off-by: Hao Wu <hao.wu@rubrik.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>Code:commit b2cf0bed6817e283ec1708bc2ca3bb5d8b9f0f4f
Author: Ye Bin <yebin10@huawei.com>
Date: Wed Oct 20 15:39:59 2021 +0800

nbd: Fix use-after-free in pid_show

[ Upstream commit 0c98057be9efa32de78dbc4685fc73da9d71faa1 ]

I got issue as follows:
[ 263.886511] BUG: KASAN: use-after-free in pid_show+0x11f/0x13f
[ 263.888359] Read of size 4 at addr ffff8880bf0648c0 by task cat/746
[ 263.890479] CPU: 0 PID: 746 Comm: cat Not tainted 4.19.90-dirty #140
[ 263.893162] Call Trace:
[ 263.893509] dump_stack+0x108/0x15f
[ 263.893999] print_address_description+0xa5/0x372
[ 263.894641] kasan_report.cold+0x236/0x2a8
[ 263.895696] __asan_report_load4_noabort+0x25/0x30
[ 263.896365] pid_show+0x11f/0x13f
[ 263.897422] dev_attr_show+0x48/0x90
[ 263.898361] sysfs_kf_seq_show+0x24d/0x4b0
[ 263.899479] kernfs_seq_show+0x14e/0x1b0
[ 263.900029] seq_read+0x43f/0x1150
[ 263.900499] kernfs_fop_read+0xc7/0x5a0
[ 263.903764] vfs_read+0x113/0x350
[ 263.904231] ksys_read+0x103/0x270
[ 263.905230] __x64_sys_read+0x77/0xc0
[ 263.906284] do_syscall_64+0x106/0x360
[ 263.906797] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reproduce this issue as follows:
1. nbd-server 8000 /tmp/disk
2. nbd-client localhost 8000 /dev/nbd1
3. cat /sys/block/nbd1/pid
Then trigger use-after-free in pid_show.

Reason is after do step '2', nbd-client progress is already exit. So
it's task_struct already freed.
To solve this issue, revert part of 6521d39a64b3's modify and remove
useless 'recv_task' member of nbd_device.

Fixes: 6521d39a64b3 ("nbd: Remove variable 'pid'")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20211020073959.2679255-1-yebin10@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>Code:commit e24f9679c3c039cc8ec80beff2239a3240176e37
Author: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Date: Mon Oct 25 10:30:37 2021 +0100

Revert "wcn36xx: Enable firmware link monitoring"

[ Upstream commit 43ea9bd84f27d06482cc823d9749cc9dd2993bc8 ]

Firmware link offload monitoring can be made to work in 3/4 cases by
switching on firmware feature bit WLANACTIVE_OFFLOAD

- Secure power-save on
- Secure power-save off
- Open power-save on

However, with an open AP if we switch off power-saving - thus never
entering Beacon Mode Power Save - BMPS, firmware never forwards loss
of beacon upwards.

We had hoped that WLANACTIVE_OFFLOAD and some fixes for sequence numbers
would unblock this but, it hasn't and further investigation is required.

Its possible to have a complete set of Secure power-save on/off and Open
power-save on/off provided we use Linux' link monitoring mechanism.

While we debug the Open AP failure we need to fix upstream.

This reverts commit c973fdad79f6eaf247d48b5fc77733e989eb01e1.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211025093037.3966022-2-bryan.odonoghue@linaro.org
Signed-off-by: Sasha Levin <sashal@kernel.org>Code:commit 8b09d36daf476ad2a03d691a6336d0d1c515e04c
Author: Johan Hovold <johan@kernel.org>
Date: Thu Oct 7 15:31:46 2021 +0200

Revert "serial: 8250: Fix reporting real baudrate value in c_ospeed field"

commit d02b006b29de14968ba4afa998bede0d55469e29 upstream.

This reverts commit 32262e2e429cdb31f9e957e997d53458762931b7.

The commit in question claims to determine the inverse of
serial8250_get_divisor() but failed to notice that some drivers override
the default implementation using a get_divisor() callback.

This means that the computed line-speed values can be completely wrong
and results in regular TCSETS requests failing (the incorrect values
would also be passed to any overridden set_divisor() callback).

Similarly, it also failed to honour the old (deprecated) ASYNC_SPD_FLAGS
and would break applications relying on those when re-encoding the
actual line speed.

There are also at least two quirks, UART_BUG_QUOT and an OMAP1510
workaround, which were happily ignored and that are now broken.

Finally, even if the offending commit were to be implemented correctly,
this is a new feature and not something which should be backported to
stable.

Cc: Pali Rohir <pali@kernel.org>
Fixes: 32262e2e429c ("serial: 8250: Fix reporting real baudrate value in c_ospeed field")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20211007133146.28949-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>Code:commit 46fd62b26822e1a33cffd8c22340e829b00c9d4c
Author: Eric Whitney <enwlinux@gmail.com>
Date: Tue Oct 12 13:19:01 2021 -0400

Revert "ext4: enforce buffer head state assertion in ext4_da_map_blocks"

commit 3eda41df05d6ad5c825cbc7fef03d563597b1afa upstream.

This reverts commit 948ca5f30e1df0c11eb5b0f410b9ceb97fa77ad9.

Two crash reports from users running variations on 5.15-rc4 kernels
suggest that it is premature to enforce the state assertion in the
original commit. Both crashes were triggered by BUG calls in that
code, indicating that under some rare circumstance the buffer head
state did not match a delayed allocated block at the time the
block was written out. No reproducer is available. Resolving this
problem will require more time than remains in the current release
cycle, so reverting the original patch for the time being is necessary
to avoid any instability it may cause.

Signed-off-by: Eric Whitney <enwlinux@gmail.com>
Link: https://lore.kernel.org/r/20211012171901.5352-1-enwlinux@gmail.com
Fixes: 948ca5f30e1d ("ext4: enforce buffer head state assertion in ext4_da_map_blocks")
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>latest?d=yIl2AUoC8zA latest?i=YkURXj-l-aA:Bj-rLd8XuGU:F7zBnMy latest?i=YkURXj-l-aA:Bj-rLd8XuGU:V_sGLiP latest?d=qj6IDK7rITs latest?i=YkURXj-l-aA:Bj-rLd8XuGU:gIN9vFw
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