linux-kernel - Re: [PATCH] pmem: fix the crash when unbind namespaces

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Date:   Tue, 24 Aug 2021 15:18:24 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     sumiyawang@...il.com
Cc:     Vishal L Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        "Weiny, Ira" <ira.weiny@...el.com>,
        Linux NVDIMM <nvdimm@...ts.linux.dev>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        lidongchen@...cent.com, sumiyawang <sumiyawang@...cent.com>
Subject: Re: [PATCH] pmem: fix the crash when unbind namespaces

On Sun, Aug 22, 2021 at 4:49 AM <sumiyawang@...il.com> wrote:
>
> From: sumiyawang <sumiyawang@...cent.com>
>
> kernel will crash when use after free the ioremap space,
> which is triggered by ndctl destroy-namespace while some IO operations
> exist.
> The sequence of pmem driver release chain should be changed:
> freeze the queue and wait io finished first, then iounmap.
>
> [47202.018374] BUG: unable to handle page fault for address: ffffc90080200000
> [47202.018822] CPU: 36 PID: 9606 Comm: systemd-udevd
> [47202.020921] Call Trace:
> [47202.020969]  ? pmem_do_bvec+0xf9/0x3a0
> [47202.021036]  ? xas_alloc+0x55/0xd0
> [47202.021094]  pmem_rw_page+0x4b/0x80
> [47202.021159]  bdev_read_page+0x86/0xb0
> [47202.021222]  do_mpage_readpage+0x5d4/0x7a0
> [47202.021297]  ? lru_cache_add+0xe/0x10
> [47202.021359]  mpage_readpages+0xf9/0x1c0
> [47202.021428]  ? bd_link_disk_holder+0x1a0/0x1a0
> [47202.021506]  blkdev_readpages+0x1d/0x20
> [47202.021574]  read_pages+0x67/0x1a0
>
> ndctl Call Trace in vmcore:
> PID: 23473  TASK: ffff88c4fbbe8000  CPU: 1   COMMAND: "ndctl"
> __schedule
> schedule
> blk_mq_freeze_queue_wait
> blk_freeze_queue
> blk_cleanup_queue
> pmem_release_queue
> devm_action_release
> release_nodes
> devres_release_all
> device_release_driver_internal
> device_driver_detach
> unbind_store
>
> At that time, the ioremap space is released

Thanks, looks good. I reworded the changelog a bit and added a "Cc:
stable" as well as a "Fixes: 50f44ee7248a ("mm/devm_memremap_pages:
fix final page put race")" tag. I'll send this up during the v5.15
merge window.

https://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm.git/commit/?h=libnvdimm-fixes&id=32b2397c