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[34.16.192.132]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-32b9be55c1esm13070183a91.9.2025.09.08.13.30.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Sep 2025 13:30:06 -0700 (PDT) Date: Mon, 8 Sep 2025 20:30:01 +0000 From: Peilin Ye To: Shakeel Butt Cc: bpf@vger.kernel.org, Alexei Starovoitov , Johannes Weiner , Tejun Heo , Roman Gushchin , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Kumar Kartikeya Dwivedi , Josh Don , Barret Rhoden , linux-mm@kvack.org Subject: Re: [PATCH bpf] bpf/helpers: Use __GFP_HIGH instead of GFP_ATOMIC in __bpf_async_init() Message-ID: References: <20250905234547.862249-1-yepeilin@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: dr84hrtnbygxa7bbdru79w999bdowpus X-Rspamd-Queue-Id: C1AA1C0011 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1757363408-784733 X-HE-Meta: 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 3CxeZCet 2RZv2l8jY+Kra6nqe9yRkFIPjCq2UUE2Ps5g8V0mE6/ErlSh+Z2nXsD/nHm2OFHnkcAyRnFiIRD8sOhbRxcbzZoUCfUgu3JYCWHOSplLmdQSLrRpctGetuRy0iNSgsQnBA20mXwcpSCPBobtWf/SP/kyo2+wtTy6jR1ubc1ilVvPfvcLGhbEhED487PrDfBnMtiL/VNDv0YzQ0HhdRZan2CdwLfE59iLPBurPaN/DYMBl8sBKVeqV57KRchLaTHh69q84VcVUIYC7hmDPxKViTzeuN7jnfubmm07GxEsgOFYCr0yZP5h4lReLQXXifPjjal3PuSrL91J313Ahi7V1ZYMWgCY8ubge1IFVXv54BM/YyCUPY9pcfL2JW5+cPsvOc+aUR+MojknLR6qyIFgrX9cs/kx4E2shLMWNaqDI8kz7nIOmacw7qT1taUTV2a3tl6novfCykqp4DglH8PY+JHu46JcEyxMdK3Qy X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 08, 2025 at 10:32:29AM -0700, Shakeel Butt wrote: > On Fri, Sep 05, 2025 at 11:45:46PM +0000, Peilin Ye wrote: > > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c > > index b9b0c5fe33f6..508b13c24778 100644 > > --- a/kernel/bpf/helpers.c > > +++ b/kernel/bpf/helpers.c > > @@ -1274,8 +1274,14 @@ static int __bpf_async_init(struct bpf_async_kern *async, struct bpf_map *map, u > > goto out; > > } > > > > - /* allocate hrtimer via map_kmalloc to use memcg accounting */ > > - cb = bpf_map_kmalloc_node(map, size, GFP_ATOMIC, map->numa_node); > > + /* Allocate via bpf_map_kmalloc_node() for memcg accounting. Use > > + * __GFP_HIGH instead of GFP_ATOMIC to avoid calling > > + * cgroup_file_notify() if an MEMCG_MAX event is raised by > > + * try_charge_memcg(). This prevents various locking issues, including > > + * double-acquiring locks that may already be held here (e.g., > > + * cgroup_file_kn_lock, rq_lock). > > Too much unnecessary information in the comment. Just mention that we > want nolock allocations and for that we need to remove __GFP_RECLAIM > flags until nolock allocation interfaces are available. Got it - I'll reword in v2. Thanks, Peilin Ye