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dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: BD4AEE000129 X-Stat-Signature: ggpwub54wo71ab9jxb88idtwxp8p8618 Received-SPF: none (nec.com>: No applicable sender policy available) receiver=imf21; identity=mailfrom; envelope-from=""; helo=JPN01-OS2-obe.outbound.protection.outlook.com; client-ip=40.107.141.74 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620864631-897809 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2021/05/13 1:31, Yang Shi wrote: > On Wed, May 12, 2021 at 5:36 AM Shakeel Butt wrote: >> >> +Tejun Heo >> >> On Wed, May 12, 2021 at 3:48 AM NOMURA JUNICHI(=1B$BLnB> wrote: >>> With the commit 476b30a0949a, if a memcg-aware shrinker is registered b= efore >>> cgroup_init(), shrinker->nr_deferred is NULL. However xchg_nr_deferred= () >>> tries to use it as memcg is turned off via "cgroup_disable=3Dmemory". >>> >>> Any thoughts? >=20 > Thanks for the report. >=20 >> >> Is there a way to find the call chain of "memcg-aware shrinker is >> registered before cgroup_init()"? >=20 > Other than adding some printk in prealloc_memcg_shrinker() then > checking out the output of dmesg I didn't think of a better way. Not > sure if we have something like early trace. This is the first registration of memcg-aware shrinker: [ 1.933693] Call Trace: [ 1.934694] sget_fc+0x20d/0x2f0 [ 1.935693] ? compare_single+0x10/0x10 [ 1.936693] ? shmem_create+0x30/0x30 [ 1.937693] vfs_get_super+0x3e/0x100 [ 1.938693] get_tree_nodev+0x16/0x20 [ 1.939693] shmem_get_tree+0x15/0x20 [ 1.940693] vfs_get_tree+0x2a/0xc0 [ 1.941693] fc_mount+0x12/0x40 [ 1.942693] vfs_kern_mount.part.43+0x61/0xa0 [ 1.943693] kern_mount+0x24/0x40 [ 1.944693] shmem_init+0x5c/0xc8 [ 1.945693] mnt_init+0x12f/0x24a [ 1.946693] ? __percpu_counter_init+0x8f/0xb0 [ 1.947693] vfs_caches_init+0xce/0xda [ 1.948693] start_kernel+0x479/0x4e3 [ 1.949693] x86_64_start_reservations+0x24/0x26 [ 1.950693] x86_64_start_kernel+0x8a/0x8d [ 1.951693] secondary_startup_64_no_verify+0xc2/0xcb That is done after command line parsing but before cgroup_init. >> Irrespective I think we can revert a3e72739b7a7e ("cgroup: fix too >> early usage of static_branch_disable()") as 6041186a3258 ("init: >> initialize jump labels before command line option parsing") has moved >> the initialization of jump labels before command line parsing. >=20 > Seems make sense to me. If some memcg aware shrinker is registered > before cgroup_init(), the mem_cgroup_disabled() check in > prealloc_memcg_shrinker() would return false negative. And I don't > think any shrinker could be registered before parsing boot > commandline. Thank you. Shakeel 's patch works for me: [PATCH] cgroup: disable controllers at parse time https://lore.kernel.org/linux-mm/20210512201946.2949351-1-shakeelb@googl= e.com/ --=20 Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.=