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In case of an early failure in dasd_init, dasd_proc_init is never called and /proc/dasd* files are never created. That can happen, for example, if an incompatible or incorrect argument is provided to the dasd_mod.dasd= kernel parameter. However, the attempted removal of /proc/dasd* files causes 8 warnings and backtraces in this case. 4 on the error path within dasd_init and 4 when the dasd module is unloaded. Notice the "removing permanent /proc entry 'devices'" message that is caused by the dasd_proc_exit function trying to remove /proc/devices instead of /proc/dasd/devices since dasd_proc_root_entry is NULL and /proc/devices is indeed permanent. Example: ------------[ cut here ]------------ removing permanent /proc entry 'devices' WARNING: CPU: 6 PID: 557 at fs/proc/generic.c:701 remove_proc_entry+0x22e/0x240 CPU: 6 PID: 557 Comm: modprobe Not tainted 6.10.5-1-default #1 openSUSE Tumbleweed f6917bfd6e5a5c7a7e900e0e3b517786fb5c6301 Hardware name: QEMU 8561 QEMU (KVM/Linux) Krnl PSW : 0704c00180000000 000003fffed0e9f2 (remove_proc_entry+0x232/0x240) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 Krnl GPRS: 000003ff00000027 000003ff00000023 0000000000000028 000002f200000000 000002f3f05bec20 0000037ffecfb7d0 000003ffffdabab0 000003ff7ee4ec72 000003ff7ee4ec72 0000000000000007 000002f280e22600 000002f280e22688 000003ffa252cfa0 0000000000010000 000003fffed0e9ee 0000037ffecfba38 Krnl Code: 000003fffed0e9e2: c020004e7017 larl %r2,000003ffff6dca10 000003fffed0e9e8: c0e5ffdfad24 brasl %r14,000003fffe904430 #000003fffed0e9ee: af000000 mc 0,0 >000003fffed0e9f2: a7f4ff4c brc 15,000003fffed0e88a 000003fffed0e9f6: 0707 bcr 0,%r7 000003fffed0e9f8: 0707 bcr 0,%r7 000003fffed0e9fa: 0707 bcr 0,%r7 000003fffed0e9fc: 0707 bcr 0,%r7 Call Trace: [<000003fffed0e9f2>] remove_proc_entry+0x232/0x240 ([<000003fffed0e9ee>] remove_proc_entry+0x22e/0x240) [<000003ff7ef5a084>] dasd_proc_exit+0x34/0x60 [dasd_mod] [<000003ff7ef560c2>] dasd_exit+0x22/0xc0 [dasd_mod] [<000003ff7ee5a26e>] dasd_init+0x26e/0x280 [dasd_mod] [<000003fffe8ac9d0>] do_one_initcall+0x40/0x220 [<000003fffe9bc758>] do_init_module+0x78/0x260 [<000003fffe9bf3a6>] __do_sys_init_module+0x216/0x250 [<000003ffff37ac9e>] __do_syscall+0x24e/0x2d0 [<000003ffff38cca8>] system_call+0x70/0x98 Last Breaking-Event-Address: [<000003fffef7ea20>] __s390_indirect_jump_r14+0x0/0x10 ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ While the cause is a user failure, the dasd module should handle the situation more gracefully. One of the simplest solutions is to make removal of the /proc/dasd* entries idempotent. Signed-off-by: Miroslav Franc <mfranc@suse.cz> [ sth: shortened if clause ] Signed-off-by: Stefan Haberland <sth@linux.ibm.com> Link: https://lore.kernel.org/r/20241108133913.3068782-2-sth@linux.ibm.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.