From: Zanxiong Qiu <zqiu2000@xxxxxxx>
get_cpu_var() calls preempt_disable(), while on RT kernel,
pagevec_lru_move_fn() will call spinlock and might schedule
the context out and hence the schedule bug occurred, issue
is found on 5.4.70-rt40 and reproducable on 5.4.74-rt41.
[ 306.340109] BUG: scheduling while atomic: stress-ng-vm/3361/0x00000002
...
[ 306.340143] Preemption disabled at:
[ 306.340143] [<ffffffffaa42c2fd>] deactivate_page+0x5d/0x110
...
[ 306.340151] Call Trace:
[ 306.340153] dump_stack+0x50/0x70
[ 306.340157] ? deactivate_page+0x5d/0x110
[ 306.340158] __schedule_bug.cold+0x89/0x96
[ 306.340160] __schedule+0x576/0x860
[ 306.340163] ? _raw_spin_lock+0x13/0x30
[ 306.340164] schedule+0x43/0xd0
[ 306.340166] rt_spin_lock_slowlock_locked+0x117/0x2c0
[ 306.340168] ? __activate_page+0x2f0/0x2f0
[ 306.340169] rt_spin_lock_slowlock+0x51/0x80
[ 306.340171] pagevec_lru_move_fn+0x62/0xc0
[ 306.340172] deactivate_page+0xb3/0x110
[ 306.340174] madvise_cold_or_pageout_pte_range+0x277/0x2d0
[ 306.340176] ? free_unref_page_list+0x3ac/0x3c0
[ 306.340177] __walk_page_range+0x1f4/0x490
[ 306.340181] walk_page_range+0x89/0x110
[ 306.340182] madvise_cold+0x7e/0xc0
[ 306.340183] ? syscall_return_via_sysret+0xf/0x7f
[ 306.340185] ? __switch_to_asm+0x34/0x70
[ 306.340186] ? __switch_to_asm+0x40/0x70
[ 306.340187] ? __switch_to_asm+0x34/0x70
[ 306.340188] ? __switch_to_asm+0x40/0x70
[ 306.340188] ? _raw_spin_unlock_irq+0x17/0x50
[ 306.340189] ? find_vma+0x16/0x70
[ 306.340190] __do_sys_madvise+0x328/0x810
[ 306.340193] ? do_syscall_64+0x67/0x1f0
[ 306.340195] do_syscall_64+0x67/0x1f0
[ 306.340196] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 306.340197] RIP: 0033:0x7f12e177510b
2154a0abcc9 ("mm: Revert the DEFINE_PER_CPU_PAGEVEC implementation")
reverted the lock/unlock_swap_pvec function, however, get_cpu_var()
was added back in deactivate_page(), actually, get_locked_var()
shall be used instead to avoid preempt_disable() call for RT.
Signed-off-by: Zanxiong Qiu <zqiu2000@xxxxxxx>
---
mm/swap.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/swap.c b/mm/swap.c
index cdb4f1fa3a48..463cac334fcf 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -666,12 +666,13 @@ void deactivate_file_page(struct page *page)
void deactivate_page(struct page *page)
{
if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
- struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
+ struct pagevec *pvec = &get_locked_var(swapvec_lock,
+ lru_deactivate_pvecs);
get_page(page);
if (!pagevec_add(pvec, page) || PageCompound(page))
pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
- put_cpu_var(lru_deactivate_pvecs);
+ put_locked_var(swapvec_lock, lru_deactivate_pvecs);
}
}
--
2.17.1
