Commit dda1c41a authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Andrew Morton
Browse files

mm: multi-gen LRU: move lru_gen_add_mm() out of IRQ-off region 

lru_gen_add_mm() has been added within an IRQ-off region in the commit
mentioned below.  The other invocations of lru_gen_add_mm() are not within
an IRQ-off region.

The invocation within IRQ-off region is problematic on PREEMPT_RT because
the function is using a spin_lock_t which must not be used within
IRQ-disabled regions.

The other invocations of lru_gen_add_mm() occur while
task_struct::alloc_lock is acquired.  Move lru_gen_add_mm() after
interrupts are enabled and before task_unlock().

Link: https://lkml.kernel.org/r/20221026134830.711887-1-bigeasy@linutronix.de


Fixes: bd74fdae ("mm: multi-gen LRU: support page table walks")
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: default avatarYu Zhao <yuzhao@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1b9c9183

fs/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -1012,7 +1012,6 @@ static int exec_mmap(struct mm_struct *mm) 
	active_mm = tsk->active_mm;

	tsk->active_mm = mm;

	tsk->mm = mm;

	lru_gen_add_mm(mm);

	/*

	 * This prevents preemption while active_mm is being loaded and

	 * it and mm are being updated, which could cause problems for
@@ -1025,6 +1024,7 @@ static int exec_mmap(struct mm_struct *mm) 
	activate_mm(active_mm, mm);

	if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))

		local_irq_enable();

	lru_gen_add_mm(mm);

	task_unlock(tsk);

	lru_gen_use_mm(mm);

	if (old_mm) {