@@ -390,16 +390,15 @@ static void blk_mq_sysfs_init(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
- int i, j;
+ int i;
kobject_init(&q->mq_kobj, &blk_mq_ktype);
- queue_for_each_hw_ctx(q, hctx, i) {
+ queue_for_each_hw_ctx(q, hctx, i)
kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
- hctx_for_each_ctx(hctx, ctx, j)
- kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
- }
+ queue_for_each_ctx(q, ctx, i)
+ kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
}
int blk_mq_register_disk(struct gendisk *disk)
This is a note to let you know that I have just added a patch titled blk-mq: Fix uninitialized kobject at CPU hotplugging to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt4. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From c3c75b210963cdbf3ff1cb62d4445d80c23918cb Mon Sep 17 00:00:00 2001 From: Takashi Iwai <tiwai@suse.de> Date: Wed, 10 Dec 2014 16:38:30 +0100 Subject: blk-mq: Fix uninitialized kobject at CPU hotplugging commit 06a41a99d13d8e919e9a00a4849e6b85ae492592 upstream. When a CPU is hotplugged, the current blk-mq spews a warning like: kobject '(null)' (ffffe8ffffc8b5d8): tried to add an uninitialized object, something is seriously wrong. CPU: 1 PID: 1386 Comm: systemd-udevd Not tainted 3.18.0-rc7-2.g088d59b-default #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_171129-lamiak 04/01/2014 0000000000000000 0000000000000002 ffffffff81605f07 ffffe8ffffc8b5d8 ffffffff8132c7a0 ffff88023341d370 0000000000000020 ffff8800bb05bd58 ffff8800bb05bd08 000000000000a0a0 000000003f441940 0000000000000007 Call Trace: [<ffffffff81005306>] dump_trace+0x86/0x330 [<ffffffff81005644>] show_stack_log_lvl+0x94/0x170 [<ffffffff81006d21>] show_stack+0x21/0x50 [<ffffffff81605f07>] dump_stack+0x41/0x51 [<ffffffff8132c7a0>] kobject_add+0xa0/0xb0 [<ffffffff8130aee1>] blk_mq_register_hctx+0x91/0xb0 [<ffffffff8130b82e>] blk_mq_sysfs_register+0x3e/0x60 [<ffffffff81309298>] blk_mq_queue_reinit_notify+0xf8/0x190 [<ffffffff8107cfdc>] notifier_call_chain+0x4c/0x70 [<ffffffff8105fd23>] cpu_notify+0x23/0x50 [<ffffffff81060037>] _cpu_up+0x157/0x170 [<ffffffff810600d9>] cpu_up+0x89/0xb0 [<ffffffff815fa5b5>] cpu_subsys_online+0x35/0x80 [<ffffffff814323cd>] device_online+0x5d/0xa0 [<ffffffff81432485>] online_store+0x75/0x80 [<ffffffff81236a5a>] kernfs_fop_write+0xda/0x150 [<ffffffff811c5532>] vfs_write+0xb2/0x1f0 [<ffffffff811c5f42>] SyS_write+0x42/0xb0 [<ffffffff8160c4ed>] system_call_fastpath+0x16/0x1b [<00007f0132fb24e0>] 0x7f0132fb24e0 This is indeed because of an uninitialized kobject for blk_mq_ctx. The blk_mq_ctx kobjects are initialized in blk_mq_sysfs_init(), but it goes loop over hctx_for_each_ctx(), i.e. it initializes only for online CPUs. Thus, when a CPU is hotplugged, the ctx for the newly onlined CPU is registered without initialization. This patch fixes the issue by initializing the all ctx kobjects belonging to each queue. Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=908794 Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- block/blk-mq-sysfs.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) -- 2.1.4