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Message-ID: <637F7527.8060307@huawei.com>
Date: Thu, 24 Nov 2022 21:44:07 +0800
From: "yebin (H)" <yebin10@...wei.com>
To: <axboe@...nel.dk>, <linux-block@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
CC: <ming.lei@...hat.com>
Subject: Re: [PATCH] blk-mq: fix possible memleak when register 'hctx' failed
ping...
On 2022/11/17 10:29, Ye Bin wrote:
> From: Ye Bin <yebin10@...wei.com>
>
> There's issue as follows when do fault injection test:
> unreferenced object 0xffff888132a9f400 (size 512):
> comm "insmod", pid 308021, jiffies 4324277909 (age 509.733s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 08 f4 a9 32 81 88 ff ff ...........2....
> 08 f4 a9 32 81 88 ff ff 00 00 00 00 00 00 00 00 ...2............
> backtrace:
> [<00000000e8952bb4>] kmalloc_node_trace+0x22/0xa0
> [<00000000f9980e0f>] blk_mq_alloc_and_init_hctx+0x3f1/0x7e0
> [<000000002e719efa>] blk_mq_realloc_hw_ctxs+0x1e6/0x230
> [<000000004f1fda40>] blk_mq_init_allocated_queue+0x27e/0x910
> [<00000000287123ec>] __blk_mq_alloc_disk+0x67/0xf0
> [<00000000a2a34657>] 0xffffffffa2ad310f
> [<00000000b173f718>] 0xffffffffa2af824a
> [<0000000095a1dabb>] do_one_initcall+0x87/0x2a0
> [<00000000f32fdf93>] do_init_module+0xdf/0x320
> [<00000000cbe8541e>] load_module+0x3006/0x3390
> [<0000000069ed1bdb>] __do_sys_finit_module+0x113/0x1b0
> [<00000000a1a29ae8>] do_syscall_64+0x35/0x80
> [<000000009cd878b0>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
>
> Fault injection context as follows:
> kobject_add
> blk_mq_register_hctx
> blk_mq_sysfs_register
> blk_register_queue
> device_add_disk
> null_add_dev.part.0 [null_blk]
>
> As 'blk_mq_register_hctx' may already add some objects when failed halfway,
> but there isn't do fallback, caller don't know which objects add failed.
> To solve above issue just do fallback when add objects failed halfway in
> 'blk_mq_register_hctx'.
>
> Signed-off-by: Ye Bin <yebin10@...wei.com>
> ---
> block/blk-mq-sysfs.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
> index 93997d297d42..4515288fbe35 100644
> --- a/block/blk-mq-sysfs.c
> +++ b/block/blk-mq-sysfs.c
> @@ -185,7 +185,7 @@ static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx)
> {
> struct request_queue *q = hctx->queue;
> struct blk_mq_ctx *ctx;
> - int i, ret;
> + int i, j, ret;
>
> if (!hctx->nr_ctx)
> return 0;
> @@ -197,9 +197,16 @@ static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx)
> hctx_for_each_ctx(hctx, ctx, i) {
> ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu);
> if (ret)
> - break;
> + goto out;
> }
>
> + return 0;
> +out:
> + hctx_for_each_ctx(hctx, ctx, j) {
> + if (j < i)
> + kobject_del(&ctx->kobj);
> + }
> + kobject_del(&hctx->kobj);
> return ret;
> }
>
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