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| author | Miaohe Lin <linmiaohe@huawei.com> | 2022-06-09 15:13:05 +0300 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-06-17 05:48:31 +0300 |
| commit | 1e57ffb6e3fd9583268c6462c4e3853575b21701 (patch) | |
| tree | 4b76609ac9ac17d254cf50fb74d9b2d9b8dd8b14 /LICENSES | |
| parent | 84c326299191042a719655d3327538fc52aa8473 (diff) | |
| download | linux-1e57ffb6e3fd9583268c6462c4e3853575b21701.tar.xz | |
mm/memremap: fix memunmap_pages() race with get_dev_pagemap()
Think about the below scene:
CPU1 CPU2
memunmap_pages
percpu_ref_exit
__percpu_ref_exit
free_percpu(percpu_count);
/* percpu_count is freed here! */
get_dev_pagemap
xa_load(&pgmap_array, PHYS_PFN(phys))
/* pgmap still in the pgmap_array */
percpu_ref_tryget_live(&pgmap->ref)
if __ref_is_percpu
/* __PERCPU_REF_ATOMIC_DEAD not set yet */
this_cpu_inc(*percpu_count)
/* access freed percpu_count here! */
ref->percpu_count_ptr = __PERCPU_REF_ATOMIC_DEAD;
/* too late... */
pageunmap_range
To fix the issue, do percpu_ref_exit() after pgmap_array is emptied. So
we won't do percpu_ref_tryget_live() against a being freed percpu_ref.
Link: https://lkml.kernel.org/r/20220609121305.2508-1-linmiaohe@huawei.com
Fixes: b7b3c01b1915 ("mm/memremap_pages: support multiple ranges per invocation")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'LICENSES')
0 files changed, 0 insertions, 0 deletions