<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/arch/xtensa/kernel, branch linux-5.14.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>Revert "sched: Add wrapper for get_wchan() to keep task blocked"</title>
<updated>2021-11-18T13:01:34+00:00</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2021-11-18T12:15:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=961913f45ff64ee68b689ae8070e1ab42108d02b'/>
<id>961913f45ff64ee68b689ae8070e1ab42108d02b</id>
<content type='text'>
This reverts commit e9ede14c116f1a6246eee89d320d60a90a86b5d5 which is
commit 42a20f86dc19f9282d974df0ba4d226c865ab9dd upstream.

It has been reported to be causing problems, and is being reworked
upstream and has been dropped from the current 5.15.y stable queue until
it gets resolved.

Reported-by: Chris Rankin &lt;rankincj@gmail.com&gt;
Reported-by: Thorsten Leemhuis &lt;linux@leemhuis.info&gt;
Link: https://lore.kernel.org/r/ed000478-2a60-0066-c337-a04bffc112b1@leemhuis.info
Cc: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Cc: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit e9ede14c116f1a6246eee89d320d60a90a86b5d5 which is
commit 42a20f86dc19f9282d974df0ba4d226c865ab9dd upstream.

It has been reported to be causing problems, and is being reworked
upstream and has been dropped from the current 5.15.y stable queue until
it gets resolved.

Reported-by: Chris Rankin &lt;rankincj@gmail.com&gt;
Reported-by: Thorsten Leemhuis &lt;linux@leemhuis.info&gt;
Link: https://lore.kernel.org/r/ed000478-2a60-0066-c337-a04bffc112b1@leemhuis.info
Cc: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Cc: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: Add wrapper for get_wchan() to keep task blocked</title>
<updated>2021-11-17T10:04:16+00:00</updated>
<author>
<name>Kees Cook</name>
<email>keescook@chromium.org</email>
</author>
<published>2021-09-29T22:02:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e9ede14c116f1a6246eee89d320d60a90a86b5d5'/>
<id>e9ede14c116f1a6246eee89d320d60a90a86b5d5</id>
<content type='text'>
[ Upstream commit 42a20f86dc19f9282d974df0ba4d226c865ab9dd ]

Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.

Suggested-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Acked-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt; [arm]
Tested-by: Mark Rutland &lt;mark.rutland@arm.com&gt; [arm64]
Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 42a20f86dc19f9282d974df0ba4d226c865ab9dd ]

Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.

Suggested-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Acked-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt; [arm]
Tested-by: Mark Rutland &lt;mark.rutland@arm.com&gt; [arm64]
Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xtensa: call irqchip_init only when CONFIG_USE_OF is selected</title>
<updated>2021-10-13T07:41:54+00:00</updated>
<author>
<name>Max Filippov</name>
<email>jcmvbkbc@gmail.com</email>
</author>
<published>2021-09-27T16:46:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8979fa2c43b07e26ed9764e31fbdeb2b08037361'/>
<id>8979fa2c43b07e26ed9764e31fbdeb2b08037361</id>
<content type='text'>
[ Upstream commit 6489f8d0e1d93a3603d8dad8125797559e4cf2a2 ]

During boot time kernel configured with OF=y but USE_OF=n displays the
following warnings and hangs shortly after starting userspace:

------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/irq/irqdomain.c:695 irq_create_mapping_affinity+0x29/0xc0
irq_create_mapping_affinity(, 6) called with NULL domain
CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.0-rc3-00001-gd67ed2510d28 #30
Call Trace:
  __warn+0x69/0xc4
  warn_slowpath_fmt+0x6c/0x94
  irq_create_mapping_affinity+0x29/0xc0
  local_timer_setup+0x40/0x88
  time_init+0xb1/0xe8
  start_kernel+0x31d/0x3f4
  _startup+0x13b/0x13b
---[ end trace 1e6630e1c5eda35b ]---
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at arch/xtensa/kernel/time.c:141 local_timer_setup+0x58/0x88
error: can't map timer irq
CPU: 0 PID: 0 Comm: swapper Tainted: G        W         5.15.0-rc3-00001-gd67ed2510d28 #30
Call Trace:
  __warn+0x69/0xc4
  warn_slowpath_fmt+0x6c/0x94
  local_timer_setup+0x58/0x88
  time_init+0xb1/0xe8
  start_kernel+0x31d/0x3f4
  _startup+0x13b/0x13b
---[ end trace 1e6630e1c5eda35c ]---
Failed to request irq 0 (timer)

Fix that by calling irqchip_init only when CONFIG_USE_OF is selected and
calling legacy interrupt controller init otherwise.

Fixes: da844a81779e ("xtensa: add device trees support")
Signed-off-by: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6489f8d0e1d93a3603d8dad8125797559e4cf2a2 ]

During boot time kernel configured with OF=y but USE_OF=n displays the
following warnings and hangs shortly after starting userspace:

------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/irq/irqdomain.c:695 irq_create_mapping_affinity+0x29/0xc0
irq_create_mapping_affinity(, 6) called with NULL domain
CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.0-rc3-00001-gd67ed2510d28 #30
Call Trace:
  __warn+0x69/0xc4
  warn_slowpath_fmt+0x6c/0x94
  irq_create_mapping_affinity+0x29/0xc0
  local_timer_setup+0x40/0x88
  time_init+0xb1/0xe8
  start_kernel+0x31d/0x3f4
  _startup+0x13b/0x13b
---[ end trace 1e6630e1c5eda35b ]---
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at arch/xtensa/kernel/time.c:141 local_timer_setup+0x58/0x88
error: can't map timer irq
CPU: 0 PID: 0 Comm: swapper Tainted: G        W         5.15.0-rc3-00001-gd67ed2510d28 #30
Call Trace:
  __warn+0x69/0xc4
  warn_slowpath_fmt+0x6c/0x94
  local_timer_setup+0x58/0x88
  time_init+0xb1/0xe8
  start_kernel+0x31d/0x3f4
  _startup+0x13b/0x13b
---[ end trace 1e6630e1c5eda35c ]---
Failed to request irq 0 (timer)

Fix that by calling irqchip_init only when CONFIG_USE_OF is selected and
calling legacy interrupt controller init otherwise.

Fixes: da844a81779e ("xtensa: add device trees support")
Signed-off-by: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xtensa: use CONFIG_USE_OF instead of CONFIG_OF</title>
<updated>2021-10-13T07:41:54+00:00</updated>
<author>
<name>Randy Dunlap</name>
<email>rdunlap@infradead.org</email>
</author>
<published>2021-09-25T03:29:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c4a9836c9dd6e9a7afed4ea7b537a766f95fbaac'/>
<id>c4a9836c9dd6e9a7afed4ea7b537a766f95fbaac</id>
<content type='text'>
[ Upstream commit d67ed2510d28a1eb33171010d35cf52178cfcbdd ]

CONFIG_OF can be set by a randconfig or by a user -- without setting the
early flattree option (OF_EARLY_FLATTREE).  This causes build errors.
However, if randconfig or a user sets USE_OF in the Xtensa config,
the right kconfig symbols are set to fix the build.

Fixes these build errors:

../arch/xtensa/kernel/setup.c:67:19: error: ‘__dtb_start’ undeclared here (not in a function); did you mean ‘dtb_start’?
   67 | void *dtb_start = __dtb_start;
      |                   ^~~~~~~~~~~
../arch/xtensa/kernel/setup.c: In function 'xtensa_dt_io_area':
../arch/xtensa/kernel/setup.c:201:14: error: implicit declaration of function 'of_flat_dt_is_compatible'; did you mean 'of_machine_is_compatible'? [-Werror=implicit-function-declaration]
  201 |         if (!of_flat_dt_is_compatible(node, "simple-bus"))
../arch/xtensa/kernel/setup.c:204:18: error: implicit declaration of function 'of_get_flat_dt_prop' [-Werror=implicit-function-declaration]
  204 |         ranges = of_get_flat_dt_prop(node, "ranges", &amp;len);
../arch/xtensa/kernel/setup.c:204:16: error: assignment to 'const __be32 *' {aka 'const unsigned int *'} from 'int' makes pointer from integer without a cast [-Werror=int-conversion]
  204 |         ranges = of_get_flat_dt_prop(node, "ranges", &amp;len);
      |                ^
../arch/xtensa/kernel/setup.c: In function 'early_init_devtree':
../arch/xtensa/kernel/setup.c:228:9: error: implicit declaration of function 'early_init_dt_scan'; did you mean 'early_init_devtree'? [-Werror=implicit-function-declaration]
  228 |         early_init_dt_scan(params);
../arch/xtensa/kernel/setup.c:229:9: error: implicit declaration of function 'of_scan_flat_dt' [-Werror=implicit-function-declaration]
  229 |         of_scan_flat_dt(xtensa_dt_io_area, NULL);

xtensa-elf-ld: arch/xtensa/mm/mmu.o:(.text+0x0): undefined reference to `xtensa_kio_paddr'

Fixes: da844a81779e ("xtensa: add device trees support")
Fixes: 6cb971114f63 ("xtensa: remap io area defined in device tree")
Signed-off-by: Randy Dunlap &lt;rdunlap@infradead.org&gt;
Signed-off-by: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit d67ed2510d28a1eb33171010d35cf52178cfcbdd ]

CONFIG_OF can be set by a randconfig or by a user -- without setting the
early flattree option (OF_EARLY_FLATTREE).  This causes build errors.
However, if randconfig or a user sets USE_OF in the Xtensa config,
the right kconfig symbols are set to fix the build.

Fixes these build errors:

../arch/xtensa/kernel/setup.c:67:19: error: ‘__dtb_start’ undeclared here (not in a function); did you mean ‘dtb_start’?
   67 | void *dtb_start = __dtb_start;
      |                   ^~~~~~~~~~~
../arch/xtensa/kernel/setup.c: In function 'xtensa_dt_io_area':
../arch/xtensa/kernel/setup.c:201:14: error: implicit declaration of function 'of_flat_dt_is_compatible'; did you mean 'of_machine_is_compatible'? [-Werror=implicit-function-declaration]
  201 |         if (!of_flat_dt_is_compatible(node, "simple-bus"))
../arch/xtensa/kernel/setup.c:204:18: error: implicit declaration of function 'of_get_flat_dt_prop' [-Werror=implicit-function-declaration]
  204 |         ranges = of_get_flat_dt_prop(node, "ranges", &amp;len);
../arch/xtensa/kernel/setup.c:204:16: error: assignment to 'const __be32 *' {aka 'const unsigned int *'} from 'int' makes pointer from integer without a cast [-Werror=int-conversion]
  204 |         ranges = of_get_flat_dt_prop(node, "ranges", &amp;len);
      |                ^
../arch/xtensa/kernel/setup.c: In function 'early_init_devtree':
../arch/xtensa/kernel/setup.c:228:9: error: implicit declaration of function 'early_init_dt_scan'; did you mean 'early_init_devtree'? [-Werror=implicit-function-declaration]
  228 |         early_init_dt_scan(params);
../arch/xtensa/kernel/setup.c:229:9: error: implicit declaration of function 'of_scan_flat_dt' [-Werror=implicit-function-declaration]
  229 |         of_scan_flat_dt(xtensa_dt_io_area, NULL);

xtensa-elf-ld: arch/xtensa/mm/mmu.o:(.text+0x0): undefined reference to `xtensa_kio_paddr'

Fixes: da844a81779e ("xtensa: add device trees support")
Fixes: 6cb971114f63 ("xtensa: remap io area defined in device tree")
Signed-off-by: Randy Dunlap &lt;rdunlap@infradead.org&gt;
Signed-off-by: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'fs_for_v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs</title>
<updated>2021-07-01T19:06:39+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-07-01T19:06:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=911a2997a5b7c16b27dfe83d8e2f614e44d90f74'/>
<id>911a2997a5b7c16b27dfe83d8e2f614e44d90f74</id>
<content type='text'>
Pull misc fs updates from Jan Kara:
 "The new quotactl_fd() syscall (remake of quotactl_path() syscall that
  got introduced &amp; disabled in 5.13 cycle), and couple of udf, reiserfs,
  isofs, and writeback fixes and cleanups"

* tag 'fs_for_v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  writeback: fix obtain a reference to a freeing memcg css
  quota: remove unnecessary oom message
  isofs: remove redundant continue statement
  quota: Wire up quotactl_fd syscall
  quota: Change quotactl_path() systcall to an fd-based one
  reiserfs: Remove unneed check in reiserfs_write_full_page()
  udf: Fix NULL pointer dereference in udf_symlink function
  reiserfs: add check for invalid 1st journal block
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull misc fs updates from Jan Kara:
 "The new quotactl_fd() syscall (remake of quotactl_path() syscall that
  got introduced &amp; disabled in 5.13 cycle), and couple of udf, reiserfs,
  isofs, and writeback fixes and cleanups"

* tag 'fs_for_v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  writeback: fix obtain a reference to a freeing memcg css
  quota: remove unnecessary oom message
  isofs: remove redundant continue statement
  quota: Wire up quotactl_fd syscall
  quota: Change quotactl_path() systcall to an fd-based one
  reiserfs: Remove unneed check in reiserfs_write_full_page()
  udf: Fix NULL pointer dereference in udf_symlink function
  reiserfs: add check for invalid 1st journal block
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: Introduce task_is_running()</title>
<updated>2021-06-18T09:43:07+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2021-06-11T08:28:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b03fbd4ff24c5f075e58eb19261d5f8b3e40d7c6'/>
<id>b03fbd4ff24c5f075e58eb19261d5f8b3e40d7c6</id>
<content type='text'>
Replace a bunch of 'p-&gt;state == TASK_RUNNING' with a new helper:
task_is_running(p).

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Davidlohr Bueso &lt;dave@stgolabs.net&gt;
Acked-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20210611082838.222401495@infradead.org
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replace a bunch of 'p-&gt;state == TASK_RUNNING' with a new helper:
task_is_running(p).

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Acked-by: Davidlohr Bueso &lt;dave@stgolabs.net&gt;
Acked-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://lore.kernel.org/r/20210611082838.222401495@infradead.org
</pre>
</div>
</content>
</entry>
<entry>
<title>quota: Wire up quotactl_fd syscall</title>
<updated>2021-06-07T10:11:24+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2021-05-31T16:42:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=65ffb3d69ed3da28af85b1e4b2aaacd6c13ba28b'/>
<id>65ffb3d69ed3da28af85b1e4b2aaacd6c13ba28b</id>
<content type='text'>
Wire up the quotactl_fd syscall.

Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Wire up the quotactl_fd syscall.

Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'sched/urgent' into sched/core, to pick up fixes</title>
<updated>2021-06-03T17:00:49+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2021-06-03T17:00:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a9e906b71f963f19aabf7af59f73f37c929a5221'/>
<id>a9e906b71f963f19aabf7af59f73f37c929a5221</id>
<content type='text'>
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>quota: Disable quotactl_path syscall</title>
<updated>2021-05-17T12:39:56+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2021-05-17T12:39:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5b9fedb31e476693c90d8ee040e7d4c51b3e7cc4'/>
<id>5b9fedb31e476693c90d8ee040e7d4c51b3e7cc4</id>
<content type='text'>
In commit fa8b90070a80 ("quota: wire up quotactl_path") we have wired up
new quotactl_path syscall. However some people in LWN discussion have
objected that the path based syscall is missing dirfd and flags argument
which is mostly standard for contemporary path based syscalls. Indeed
they have a point and after a discussion with Christian Brauner and
Sascha Hauer I've decided to disable the syscall for now and update its
API. Since there is no userspace currently using that syscall and it
hasn't been released in any major release, we should be fine.

CC: Christian Brauner &lt;christian.brauner@ubuntu.com&gt;
CC: Sascha Hauer &lt;s.hauer@pengutronix.de&gt;
Link: https://lore.kernel.org/lkml/20210512153621.n5u43jsytbik4yze@wittgenstein
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In commit fa8b90070a80 ("quota: wire up quotactl_path") we have wired up
new quotactl_path syscall. However some people in LWN discussion have
objected that the path based syscall is missing dirfd and flags argument
which is mostly standard for contemporary path based syscalls. Indeed
they have a point and after a discussion with Christian Brauner and
Sascha Hauer I've decided to disable the syscall for now and update its
API. Since there is no userspace currently using that syscall and it
hasn't been released in any major release, we should be fine.

CC: Christian Brauner &lt;christian.brauner@ubuntu.com&gt;
CC: Sascha Hauer &lt;s.hauer@pengutronix.de&gt;
Link: https://lore.kernel.org/lkml/20210512153621.n5u43jsytbik4yze@wittgenstein
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/core: Initialize the idle task with preemption disabled</title>
<updated>2021-05-12T11:01:45+00:00</updated>
<author>
<name>Valentin Schneider</name>
<email>valentin.schneider@arm.com</email>
</author>
<published>2021-05-12T09:46:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674'/>
<id>f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674</id>
<content type='text'>
As pointed out by commit

  de9b8f5dcbd9 ("sched: Fix crash trying to dequeue/enqueue the idle thread")

init_idle() can and will be invoked more than once on the same idle
task. At boot time, it is invoked for the boot CPU thread by
sched_init(). Then smp_init() creates the threads for all the secondary
CPUs and invokes init_idle() on them.

As the hotplug machinery brings the secondaries to life, it will issue
calls to idle_thread_get(), which itself invokes init_idle() yet again.
In this case it's invoked twice more per secondary: at _cpu_up(), and at
bringup_cpu().

Given smp_init() already initializes the idle tasks for all *possible*
CPUs, no further initialization should be required. Now, removing
init_idle() from idle_thread_get() exposes some interesting expectations
with regards to the idle task's preempt_count: the secondary startup always
issues a preempt_disable(), requiring some reset of the preempt count to 0
between hot-unplug and hotplug, which is currently served by
idle_thread_get() -&gt; idle_init().

Given the idle task is supposed to have preemption disabled once and never
see it re-enabled, it seems that what we actually want is to initialize its
preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove
init_idle() from idle_thread_get().

Secondary startups were patched via coccinelle:

  @begone@
  @@

  -preempt_disable();
  ...
  cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

Signed-off-by: Valentin Schneider &lt;valentin.schneider@arm.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Acked-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As pointed out by commit

  de9b8f5dcbd9 ("sched: Fix crash trying to dequeue/enqueue the idle thread")

init_idle() can and will be invoked more than once on the same idle
task. At boot time, it is invoked for the boot CPU thread by
sched_init(). Then smp_init() creates the threads for all the secondary
CPUs and invokes init_idle() on them.

As the hotplug machinery brings the secondaries to life, it will issue
calls to idle_thread_get(), which itself invokes init_idle() yet again.
In this case it's invoked twice more per secondary: at _cpu_up(), and at
bringup_cpu().

Given smp_init() already initializes the idle tasks for all *possible*
CPUs, no further initialization should be required. Now, removing
init_idle() from idle_thread_get() exposes some interesting expectations
with regards to the idle task's preempt_count: the secondary startup always
issues a preempt_disable(), requiring some reset of the preempt count to 0
between hot-unplug and hotplug, which is currently served by
idle_thread_get() -&gt; idle_init().

Given the idle task is supposed to have preemption disabled once and never
see it re-enabled, it seems that what we actually want is to initialize its
preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove
init_idle() from idle_thread_get().

Secondary startups were patched via coccinelle:

  @begone@
  @@

  -preempt_disable();
  ...
  cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

Signed-off-by: Valentin Schneider &lt;valentin.schneider@arm.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Acked-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com
</pre>
</div>
</content>
</entry>
</feed>
