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* [PATCH AUTOSEL 6.3 01/14] cpu/hotplug: Reset task stack state in _cpu_up()
@ 2023-07-02 19:40 Sasha Levin
  2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 02/14] io_uring: annotate offset timeout races Sasha Levin
                   ` (12 more replies)
  0 siblings, 13 replies; 16+ messages in thread
From: Sasha Levin @ 2023-07-02 19:40 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: David Woodhouse, Thomas Gleixner, Peter Zijlstra, Mark Rutland,
	Michael Kelley, Oleksandr Natalenko, Helge Deller,
	Guilherme G . Piccoli, Sasha Levin

From: David Woodhouse <dwmw@amazon.co.uk>

[ Upstream commit 6d712b9b3a58018259fb40ddd498d1f7dfa1f4ec ]

Commit dce1ca0525bf ("sched/scs: Reset task stack state in bringup_cpu()")
ensured that the shadow call stack and KASAN poisoning were removed from
a CPU's stack each time that CPU is brought up, not just once.

This is not incorrect. However, with parallel bringup the idle thread setup
will happen at a different step. As a consequence the cleanup in
bringup_cpu() would be too late.

Move the SCS/KASAN cleanup to the generic _cpu_up() function instead,
which already ensures that the new CPU's stack is available, purely to
allow for early failure. This occurs when the CPU to be brought up is
in the CPUHP_OFFLINE state, which should correctly do the cleanup any
time the CPU has been taken down to the point where such is needed.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205257.027075560@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/cpu.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6c0a92ca6bb59..43e0a77f21e81 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -591,12 +591,6 @@ static int bringup_cpu(unsigned int cpu)
 	struct task_struct *idle = idle_thread_get(cpu);
 	int ret;
 
-	/*
-	 * Reset stale stack state from the last time this CPU was online.
-	 */
-	scs_task_reset(idle);
-	kasan_unpoison_task_stack(idle);
-
 	/*
 	 * Some architectures have to walk the irq descriptors to
 	 * setup the vector space for the cpu which comes online.
@@ -1383,6 +1377,12 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 			ret = PTR_ERR(idle);
 			goto out;
 		}
+
+		/*
+		 * Reset stale stack state from the last time this CPU was online.
+		 */
+		scs_task_reset(idle);
+		kasan_unpoison_task_stack(idle);
 	}
 
 	cpuhp_tasks_frozen = tasks_frozen;
-- 
2.39.2


^ permalink raw reply related	[flat|nested] 16+ messages in thread
end of thread, other threads:[~2023-07-02 19:45 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-07-02 19:40 [PATCH AUTOSEL 6.3 01/14] cpu/hotplug: Reset task stack state in _cpu_up() Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 02/14] io_uring: annotate offset timeout races Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 03/14] x86/amd_nb: Add MI200 PCI IDs Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 04/14] debugobjects: Recheck debug_objects_enabled before reporting Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 05/14] nbd: Add the maximum limit of allocated index in nbd_dev_add Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 06/14] md: fix data corruption for raid456 when reshape restart while grow up Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 07/14] md/raid10: prevent soft lockup while flush writes Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 08/14] scsi: sg: fix blktrace debugfs entries leakage Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 09/14] blk-mq: fix NULL dereference on q->elevator in blk_mq_elv_switch_none Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 10/14] posix-timers: Ensure timer ID search-loop limit is valid Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 11/14] btrfs: add xxhash to fast checksum implementations Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 12/14] btrfs: don't check PageError in __extent_writepage Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 13/14] btrfs: abort transaction at update_ref_for_cow() when ref count is zero Sasha Levin
2023-07-02 19:40 ` [PATCH AUTOSEL 6.3 14/14] erofs: Fix detection of atomic context Sasha Levin
2023-07-02 19:40   ` Sasha Levin
2023-07-02 19:40   ` Sasha Levin

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