a5a039b017
Currently we free the resources backing the enclosure device before we call device_unregister(). This is racy: during rmmod of low-level SCSI drivers that hook into enclosure, we end up with a small window of time during which writing to /sys can OOPS. Example trace with mpt3sas: general protection fault: 0000 [#1] SMP KASAN Modules linked in: mpt3sas(-) <...> RIP: [<ffffffffa0388a98>] ses_get_page2_descriptor.isra.6+0x38/0x220 [ses] Call Trace: [<ffffffffa0389d14>] ses_set_fault+0xf4/0x400 [ses] [<ffffffffa0361069>] set_component_fault+0xa9/0xf0 [enclosure] [<ffffffff8205bffc>] dev_attr_store+0x3c/0x70 [<ffffffff81677df5>] sysfs_kf_write+0x115/0x180 [<ffffffff81675725>] kernfs_fop_write+0x275/0x3a0 [<ffffffff8151f810>] __vfs_write+0xe0/0x3e0 [<ffffffff8152281f>] vfs_write+0x13f/0x4a0 [<ffffffff81526731>] SyS_write+0x111/0x230 [<ffffffff828b401b>] entry_SYSCALL_64_fastpath+0x13/0x94 Fortunately the solution is extremely simple: call device_unregister() before we free the resources, and the race no longer exists. The driver core holds a reference over ->remove_dev(), so AFAICT this is safe. Signed-off-by: Calvin Owens <calvinowens@fb.com> Acked-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.