On Fri, Apr 09, 2021 at 08:08:00AM +0800, Wang Yugui wrote: > Hi, > > > > kernel: at least 5.10.26/5.10.27/5.10.28 > > > > > > This problem is triggered by our application, NOT xfstests. > > > But our applicaiton have some heavy write load just like > > > xfstest/generic/476. > > > Our application use at most 75% of memory, if still not enough, > > > it will write out all buffer info to filesystem. > > > > Do you use cgroups at all? If yes can you describe the workload pattern > > a bit. > > cgroups is enabled defaultly, so cgroups is used. > > This is the output of systemd-cgls, ''samtools.nipt sort -m 60G" is one > of our application. but our application is NOT cgroups-aware, and it NOT > call any cgroup interface directly. > > Control group /: > -.slice > ├─user.slice > │ └─user-0.slice > │ ├─session-55.scope > │ │ ├─48747 sshd: root [priv] > │ │ ├─48788 sshd: root@notty > │ │ ├─48795 perl -e > @GNU_Parallel=split/_/,"use_IPC::Open3;_use_MIME::Base6... > │ │ ├─48943 samtools.nipt sort -m 60G -T > /nodetmp//nfs/biowrk/baseline.wgs2... > │ │ ├─.... > │ └─user@0.service > │ └─init.scope > │ ├─48775 /usr/lib/systemd/systemd --user > │ └─48781 (sd-pam) > ├─init.scope > │ └─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 18 > └─system.slice > ├─rngd.service > │ └─1577 /sbin/rngd -f --fill-watermark=0 > ├─irqbalance.service > │ └─1543 /usr/sbin/irqbalance --foreground > .... > > > > > This problem is happen in linux kernel 5.10.x, but not happen in linux > > > kernel 5.4.x. It have high frequency to repduce too. > > > > Ah. Can you try the following patch? > > https://lore.kernel.org/lkml/20210408035736.883861-4-g...@fb.com/ > > > > Thanks, > > Dennis > > kernel: kernel 5.10.28+this patch > result: yet not happen after 4 times test. > without this path, the reproduce frequency is >50% > > And a question about this, > > > > > upper caller: > > > > > nofs_flag = memalloc_nofs_save(); > > > > > ret = btrfs_drew_lock_init(&root->snapshot_lock); > > > > > memalloc_nofs_restore(nofs_flag); > > > > The issue is here. nofs is set which means percpu attempts an atomic > > allocation. If it cannot find anything already allocated it isn't happy. > > This was done before memalloc_nofs_{save/restore}() were pervasive. > > > > Percpu should probably try to allocate some pages if possible even if > > nofs is set. > > Should we check and pre-alloc memory inside memalloc_nofs_restore()? > another memalloc_nofs_save() may come soon. > > something like this in memalloc_nofs_save()? > if (pcpu_nr_empty_pop_pages[type] < PCPU_EMPTY_POP_PAGES_LOW) > pcpu_schedule_balance_work(); >
Percpu does do this via a workqueue item. The issue is in v5.9 we introduced 2 types of chunks. However, the free float page number was for the total. So even if 1 chunk type dropped below, the other chunk type might have enough pages. I'm queuing this for 5.12 and will send it out assuming it does fix your problem. > > by the way, this problem still happen in kernel 5.10.28+this patch. > Is this is a PANIC without OOPS? any guide for troubleshooting please. Sorry I don't follow. Above you said the problem hasn't reproed. But now you're saying it does? Does your issue still reproduce with the patch above? > > problem: > > OS/VGA console is freezed , and no call trace is outputed. > > Just some info is outputed to IPMI/dell iDRAC > > 2 | 04/03/2021 | 11:35:01 | OS Critical Stop #0x46 | Run-time critical > > stop () | Asserted > > 3 | Linux kernel panic: Fatal excep > > 4 | Linux kernel panic: tion > > Best Regards > Wang Yugui (wangyu...@e16-tech.com) > 2021/04/08 > Thanks, Dennis
