> I tried with the mods you had appended, from [PATCH v7 02/10] > discussion with Konstantion: no, still crashes in a similar way.> > Does your github tree have other changes too? I see it says "Latest > commit e05d0dd 22 days ago", which doesn't seem to fit. Afraid I > don't have time to test many variations. Thanks a lot for testing! the github version is same as your tested. The github branches page has a bug, it don't show correct update time. https://github.com/alexshi/linux/branches while detailed page does. https://github.com/alexshi/linux/tree/lru-next > > It looks like, in my case, systemd was usually jumping in and doing > something with shmem (perhaps via memfd) that read back from swap > and triggered the crash without any further intervention from me. > > So please try booting with mem=700M and 1.5G swap, > mount -t tmpfs -o size=470M tmpfs /tst > cp /dev/zero /tst; cp /tst/zero /dev/null > > That's enough to crash it for me, without getting into any losetup or > systemd complications. But you might have to adjust the numbers to be > sure of writing out and reading back from swap. > > It's swap to SSD in my case, don't think that matters. I happen to > run with swappiness 100 (precisely to help generate swap problems), > but swappiness 60 is good enough to get these crashes. > I did use 700M memory and 1.5G swapfile in my qemu, but with a swapfile not a disk. qemu-system-x86_64 -smp 4 -enable-kvm -cpu SandyBridge \ -m 700M -kernel /home/kuiliang.as/linux/qemulru/arch/x86/boot/bzImage \ -append "earlyprintk=ttyS0 root=/dev/sda1 console=ttyS0 debug crashkernel=128M printk.devkmsg=on " \ -hda /home/kuiliang.as/rootimages/CentOS-7-x86_64-Azure-1703.qcow2 \ -hdb /home/kuiliang.as/rootimages/hdb.qcow2 \ --nographic \ Anyway, although I didn't reproduced the bug. but I found a bug in my debug function: VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != page->mem_cgroup, page); if !page->mem_cgroup, the bug could be triggered, so, seems it's a bug for debug function, not real issue. The 9th patch should be replaced by the following new patch. Many thanks for testing! Alex >From ac6d3e2bcfba5727d5c03f9655bb0c7443f655eb Mon Sep 17 00:00:00 2001 From: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> Date: Mon, 23 Dec 2019 13:33:54 +0800 Subject: [PATCH v8 8/9] mm/lru: add debug checking for page memcg moving This debug patch could give some clues if there are sth out of consideration. Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: cgroups@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx --- include/linux/memcontrol.h | 5 +++++ mm/compaction.c | 2 ++ mm/memcontrol.c | 13 +++++++++++++ 3 files changed, 20 insertions(+) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 09e861df48e8..ece88bb11d0f 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -421,6 +421,7 @@ struct lruvec *lock_page_lruvec_irq(struct page *); struct lruvec *lock_page_lruvec_irqsave(struct page *, unsigned long*); void unlock_page_lruvec_irq(struct lruvec *); void unlock_page_lruvec_irqrestore(struct lruvec *, unsigned long); +void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page); struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p); @@ -1183,6 +1184,10 @@ static inline void count_memcg_event_mm(struct mm_struct *mm, enum vm_event_item idx) { } + +static inline void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page) +{ +} #endif /* CONFIG_MEMCG */ /* idx can be of type enum memcg_stat_item or node_stat_item */ diff --git a/mm/compaction.c b/mm/compaction.c index 8c0a2da217d8..151242817bf4 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -971,6 +971,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, compact_lock_irqsave(&lruvec->lru_lock, &flags, cc); locked_lruvec = lruvec; + lruvec_memcg_debug(lruvec, page); + /* Try get exclusive access under lock */ if (!skip_updated) { skip_updated = true; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 00fef8ddbd08..a473da8d2275 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1238,6 +1238,17 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd return lruvec; } +void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page) +{ + if (mem_cgroup_disabled()) + return; + + if (!page->mem_cgroup) + VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != root_mem_cgroup, page); + else + VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != page->mem_cgroup, page); +} + struct lruvec *lock_page_lruvec_irq(struct page *page) { struct lruvec *lruvec; @@ -1247,6 +1258,7 @@ struct lruvec *lock_page_lruvec_irq(struct page *page) lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page)); spin_lock_irq(&lruvec->lru_lock); + lruvec_memcg_debug(lruvec, page); return lruvec; } @@ -1259,6 +1271,7 @@ struct lruvec *lock_page_lruvec_irqsave(struct page *page, unsigned long *flags) lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page)); spin_lock_irqsave(&lruvec->lru_lock, *flags); + lruvec_memcg_debug(lruvec, page); return lruvec; } -- 2.22.0
