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Wong" To: Kent Overstreet Cc: linux-mm@kvack.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: scheduling while atomic on rc3 - migration + buffer heads Message-ID: <20250421172702.GB25655@frogsfrogsfrogs> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3614540003 X-Stat-Signature: jfqrzesdn36oky57zx76yt91uqcspir3 X-Rspam-User: X-HE-Tag: 1745256424-403826 X-HE-Meta: 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 try30lyh KDTR/H04STaH9NSYe9VxLMxw4F/jP5GrPhodMMeq054//17/Ke7EGHin5lFRfOCjQ2Qk7tR4q7T6bi0z9PwMgnRuQjOLMNreOCTnzgN3BrWeDc9ATFcehp2o+fLVSjf0O2yc21ocZsoGivhXb1NwcJfmQhX+k4iMnJxAe1k0mbXTtgNYQag/Tp1Y7p2aEerGtM1DX3GbzSukfQOG6NK9iqAf4UrF3C2GLBCLkgpupY0GGLlJP6J6AVnBHEx5yYCABzteXQjhQSIQQDazn6vaeYKjW1WU/t5t9cyRz1Lq+cAPjGdT8VXkhW0d4MWJsVfn6xAhUhIDQKa5CWDE= 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: List-Subscribe: List-Unsubscribe: On Mon, Apr 21, 2025 at 11:14:44AM -0400, Kent Overstreet wrote: > This just popped up in one of my test runs. > > Given that it's buffer heads, it has to be the ext4 root filesystem, not > bcachefs. Wrong. udev calling libblkid reading the (mounted) bdev to figure out there's a bcachefs filesystem will still create bufferheads, and possibly very large ones. willy's temporary workaround in https://lore.kernel.org/linux-fsdevel/Z_VwF1MA-R7MgDVG@casper.infradead.org/ shuts all that up enough to move on to triaging the rest of the bleeding. --D > 00465 ========= TEST lz4_buffered > 00465 > 00465 WATCHDOG 360 > 00466 bcachefs (vdb): starting version 1.25: extent_flags opts=errors=panic,compression=lz4 > 00466 bcachefs (vdb): initializing new filesystem > 00466 bcachefs (vdb): going read-write > 00466 bcachefs (vdb): marking superblocks > 00466 bcachefs (vdb): initializing freespace > 00466 bcachefs (vdb): done initializing freespace > 00466 bcachefs (vdb): reading snapshots table > 00466 bcachefs (vdb): reading snapshots done > 00466 bcachefs (vdb): done starting filesystem > 00466 starting copy > 00515 BUG: sleeping function called from invalid context at mm/util.c:743 > 00515 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 120, name: kcompactd0 > 00515 preempt_count: 1, expected: 0 > 00515 RCU nest depth: 0, expected: 0 > 00515 1 lock held by kcompactd0/120: > 00515 #0: ffffff80c0c558f0 (&mapping->i_private_lock){+.+.}-{3:3}, at: __buffer_migrate_folio+0x114/0x298 > 00515 Preemption disabled at: > 00515 [] __buffer_migrate_folio+0x114/0x298 > 00515 CPU: 11 UID: 0 PID: 120 Comm: kcompactd0 Not tainted 6.15.0-rc3-ktest-gb2a78fdf7d2f #20530 PREEMPT > 00515 Hardware name: linux,dummy-virt (DT) > 00515 Call trace: > 00515 show_stack+0x1c/0x30 (C) > 00515 dump_stack_lvl+0xb0/0xc0 > 00515 dump_stack+0x14/0x20 > 00515 __might_resched+0x180/0x288 > 00515 folio_mc_copy+0x54/0x98 > 00515 __migrate_folio.isra.0+0x68/0x168 > 00515 __buffer_migrate_folio+0x280/0x298 > 00515 buffer_migrate_folio_norefs+0x18/0x28 > 00515 migrate_pages_batch+0x94c/0xeb8 > 00515 migrate_pages_sync+0x84/0x240 > 00515 migrate_pages+0x284/0x698 > 00515 compact_zone+0xa40/0x10f8 > 00515 kcompactd_do_work+0x204/0x498 > 00515 kcompactd+0x3c4/0x400 > 00515 kthread+0x13c/0x208 > 00515 ret_from_fork+0x10/0x20 > 00518 starting sync > 00519 starting rm > 00520 ========= FAILED TIMEOUT lz4_buffered in 360s > >