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author | zijun_hu <zijun_hu@htc.com> | 2016-12-13 01:45:02 +0100 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-13 03:55:09 +0100 |
commit | 8f6066049c54ef0f726869c27d610cef5d15e084 (patch) | |
tree | f51e74b3a7158fdffa0c9f37f82fffe8fe3d537b /mm | |
parent | kasan: turn on -fsanitize-address-use-after-scope (diff) | |
download | linux-8f6066049c54ef0f726869c27d610cef5d15e084.tar.xz linux-8f6066049c54ef0f726869c27d610cef5d15e084.zip |
mm/percpu.c: fix panic triggered by BUG_ON() falsely
As shown by pcpu_build_alloc_info(), the number of units within a percpu
group is deduced by rounding up the number of CPUs within the group to
@upa boundary/ Therefore, the number of CPUs isn't equal to the units's
if it isn't aligned to @upa normally. However, pcpu_page_first_chunk()
uses BUG_ON() to assert that one number is equal to the other roughly,
so a panic is maybe triggered by the BUG_ON() incorrectly.
In order to fix this issue, the number of CPUs is rounded up then
compared with units's and the BUG_ON() is replaced with a warning and
return of an error code as well, to keep system alive as much as
possible.
Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com
Signed-off-by: zijun_hu <zijun_hu@htc.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/percpu.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index 255714302394..f696385bcc44 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -2093,6 +2093,8 @@ int __init pcpu_page_first_chunk(size_t reserved_size, size_t pages_size; struct page **pages; int unit, i, j, rc; + int upa; + int nr_g0_units; snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10); @@ -2100,7 +2102,12 @@ int __init pcpu_page_first_chunk(size_t reserved_size, if (IS_ERR(ai)) return PTR_ERR(ai); BUG_ON(ai->nr_groups != 1); - BUG_ON(ai->groups[0].nr_units != num_possible_cpus()); + upa = ai->alloc_size/ai->unit_size; + nr_g0_units = roundup(num_possible_cpus(), upa); + if (unlikely(WARN_ON(ai->groups[0].nr_units != nr_g0_units))) { + pcpu_free_alloc_info(ai); + return -EINVAL; + } unit_pages = ai->unit_size >> PAGE_SHIFT; @@ -2111,21 +2118,22 @@ int __init pcpu_page_first_chunk(size_t reserved_size, /* allocate pages */ j = 0; - for (unit = 0; unit < num_possible_cpus(); unit++) + for (unit = 0; unit < num_possible_cpus(); unit++) { + unsigned int cpu = ai->groups[0].cpu_map[unit]; for (i = 0; i < unit_pages; i++) { - unsigned int cpu = ai->groups[0].cpu_map[unit]; void *ptr; ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE); if (!ptr) { pr_warn("failed to allocate %s page for cpu%u\n", - psize_str, cpu); + psize_str, cpu); goto enomem; } /* kmemleak tracks the percpu allocations separately */ kmemleak_free(ptr); pages[j++] = virt_to_page(ptr); } + } /* allocate vm area, map the pages and copy static data */ vm.flags = VM_ALLOC; |