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authorNhat Pham <nphamcs@gmail.com>2023-10-06 20:46:26 +0200
committerAndrew Morton <akpm@linux-foundation.org>2023-10-18 23:34:17 +0200
commit4b569387c0d566db288e7c3e1b484b43df797bdb (patch)
tree2d3e4786e451d27af2618e00ffb9ddd1bbefa5cb /usr
parentmm, hugetlb: remove HUGETLB_CGROUP_MIN_ORDER (diff)
downloadlinux-4b569387c0d566db288e7c3e1b484b43df797bdb.tar.xz
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memcontrol: add helpers for hugetlb memcg accounting
Patch series "hugetlb memcg accounting", v4. Currently, hugetlb memory usage is not acounted for in the memory controller, which could lead to memory overprotection for cgroups with hugetlb-backed memory. This has been observed in our production system. For instance, here is one of our usecases: suppose there are two 32G containers. The machine is booted with hugetlb_cma=6G, and each container may or may not use up to 3 gigantic page, depending on the workload within it. The rest is anon, cache, slab, etc. We can set the hugetlb cgroup limit of each cgroup to 3G to enforce hugetlb fairness. But it is very difficult to configure memory.max to keep overall consumption, including anon, cache, slab etcetera fair. What we have had to resort to is to constantly poll hugetlb usage and readjust memory.max. Similar procedure is done to other memory limits (memory.low for e.g). However, this is rather cumbersome and buggy. Furthermore, when there is a delay in memory limits correction, (for e.g when hugetlb usage changes within consecutive runs of the userspace agent), the system could be in an over/underprotected state. This patch series rectifies this issue by charging the memcg when the hugetlb folio is allocated, and uncharging when the folio is freed. In addition, a new selftest is added to demonstrate and verify this new behavior. This patch (of 4): This patch exposes charge committing and cancelling as parts of the memory controller interface. These functionalities are useful when the try_charge() and commit_charge() stages have to be separated by other actions in between (which can fail). One such example is the new hugetlb accounting behavior in the following patch. The patch also adds a helper function to obtain a reference to the current task's memcg. Link: https://lkml.kernel.org/r/20231006184629.155543-1-nphamcs@gmail.com Link: https://lkml.kernel.org/r/20231006184629.155543-2-nphamcs@gmail.com Signed-off-by: Nhat Pham <nphamcs@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Frank van der Linden <fvdl@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tejun heo <tj@kernel.org> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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