Re: [RFC PATCH 1/3] mm: Drop locked from isolate_migratepages_block

Alex Shi
2020-08-13T07:45:46Z

在 2020/8/13 下午12:02, Alexander Duyck 写道:
> - rcu_read_lock();
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
> -
> /* If we already hold the lock, we can skip some rechecking */
> - if (lruvec != locked) {
> - if (locked)
> - unlock_page_lruvec_irqrestore(locked, flags);
> + if (!lruvec || !lruvec_holds_page_lru_lock(page, lruvec)) {

Ops, lruvec_holds_page_lru_lock need rcu_read_lock.

> + if (lruvec)
> + unlock_page_lruvec_irqrestore(lruvec, flags);
>
> + lruvec = mem_cgroup_page_lruvec(page, pgdat);
> compact_lock_irqsave(&lruvec->lru_lock, &flags, cc);
> - locked = lruvec;
> rcu_read_unlock();
>

and some bugs:
[ 534.564741] CPU: 23 PID: 545 Comm: kcompactd1 Kdump: loaded Tainted: G S W 5.8.0-next-20200803-00028-g9a7ff2cd6e5c #85
[ 534.577320] Hardware name: Alibaba Alibaba Cloud ECS/Alibaba Cloud ECS, BIOS 1.0.PL.IP.P.027.02 05/29/2020
[ 534.587693] Call Trace:
[ 534.590522] dump_stack+0x96/0xd0
[ 534.594231] ___might_sleep.cold.90+0xff/0x115
[ 534.599102] kcompactd+0x24b/0x370
[ 534.602904] ? finish_wait+0x80/0x80
[ 534.606897] ? kcompactd_do_work+0x3d0/0x3d0
[ 534.611566] kthread+0x14e/0x170
[ 534.615182] ? kthread_park+0x80/0x80
[ 534.619252] ret_from_fork+0x1f/0x30
[ 535.629483] BUG: sleeping function called from invalid context at include/linux/freezer.h:57
[ 535.638691] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 545, name: kcompactd1
[ 535.647601] INFO: lockdep is turned off.