From 255bb0ac393f1c2818cd75af45a9226300ab3daf Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 26 Oct 2022 15:48:30 +0200 Subject: [PATCH 15/29] 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: bd74fdaea1460 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Sebastian Andrzej Siewior Acked-by: Yu Zhao Cc: Al Viro Cc: "Eric W . Biederman" Cc: Kees Cook Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- fs/exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/exec.c +++ b/fs/exec.c @@ -1013,7 +1013,6 @@ static int exec_mmap(struct mm_struct *m 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 @@ -1028,6 +1027,7 @@ static int exec_mmap(struct mm_struct *m local_irq_enable(); tsk->mm->vmacache_seqnum = 0; vmacache_flush(tsk); + lru_gen_add_mm(mm); task_unlock(tsk); lru_gen_use_mm(mm); if (old_mm) {