Messages in this thread | | | From | SeongJae Park <> | Subject | [PATCH v2 0/5] avoid divide-by-zero due to max_nr_accesses overflow | Date | Fri, 20 Oct 2023 17:23:12 +0000 |
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Changes from v1 (https://lore.kernel.org/damon/20231019194924.100347-1-sj@kernel.org/) - Add Reported-by: Jakub Acs <acsjakub@amazon.de>
The maximum nr_accesses of given DAMON context can be calculated by dividing the aggregation interval by the sampling interval. Some logics in DAMON uses the maximum nr_accesses as a divisor. Hence, the value shouldn't be zero. Such case is avoided since DAMON avoids setting the agregation interval as samller than the sampling interval. However, since nr_accesses is unsigned int while the intervals are unsigned long, the maximum nr_accesses could be zero while casting.
Avoid the divide-by-zero by implementing a function that handles the corner case (first patch), and replaces the vulnerable direct max nr_accesses calculations (remaining patches).
Note that the patches for the replacements are divided for broken commits, to make backporting on required tres easier. Especially, the last patch is for a patch that not yet merged into the mainline but in mm tree.
SeongJae Park (5): mm/damon: implement a function for max nr_accesses safe calculation mm/damon/core: avoid divide-by-zero during monitoring results update mm/damon/ops-common: avoid divide-by-zero during region hotness calculation mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation mm/damon/core: avoid divide-by-zero from pseudo-moving window length calculation
include/linux/damon.h | 7 +++++++ mm/damon/core.c | 12 +++--------- mm/damon/lru_sort.c | 4 +--- mm/damon/ops-common.c | 5 ++--- 4 files changed, 13 insertions(+), 15 deletions(-)
base-commit: e845524c56a529768a8793e96304db09134eafdf -- 2.34.1
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