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b=WyFHp9GeXwJKlncsYct5wjADPuVdgkLd2uSHFbC1mG55lAXc1U8XZoWXmnfmn9Dr2 PXORo+2coJ7Mph4851ypNraMEIjoOMS5zCR3wcjtLWWfghetN0zc1n+EVb7FD2/U8l naTgQWztpPtatKKLKpxcMtowm4CHYIHi8CIt2tCvFG4729T85JbHsgYl4hOcPBSKe5 9n2GlvulkZtYJ09c13UQtPuTLY4evPQHxn6dnQSXBKuq3QzLvYB9pvF/AuT24+2u/P wkSpUmHB4p4J9mFmKtXOvNAZ9oavWEkWa3uVk5jDbifS4N5aSsiiyRilgZ5DgCNRE3 XDY810l320myw== Date: Fri, 4 Sep 2026 17:24:59 +0100 From: "Lorenzo Stoakes (ARM)" To: David Stevens Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] memcg: Don't call schedule_work when no spinning is allowed Message-ID: References: <20260831234339.280376-1-stevensd@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260831234339.280376-1-stevensd@google.com> X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3A2E5100002 X-Stat-Signature: 6x9y6amc1dyep84h1ckxhko8ww57ubp4 X-HE-Tag: 1788539106-437009 X-HE-Meta: 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 LyFeabza nYc6XvZTV3DotwNQwYrduYCaXD5bIJ+9hZomtCxXeNkBEYmxTefTXGb0hXmACyp6UdJjajbNHGWyL9KlTFdxgBsZPt7v0EfkCTQ4i0zsj/x3gVjsXUXHhpfVjudq17DXOf2dHXWIhDN/CbGt1VVyH1A56zgQ9EuC4akbcqp3Rg5CgWGRmbzaHXpUEIhYY/uL63PcF+AOVxdtPO8wHQ7z47hjd+8ekSd8DNpUgxK5eA/P+XLCXnyqLdAFs0ESnixVf2VIRpaw8scfTdF+UepJG8KnhBMgwjlgu+JwOVYBS78F9leosaF3xb8YX3Lz+tUQqSLdE Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 31, 2026 at 04:43:39PM -0700, David Stevens wrote: > Memcg charging can be done from any context, but calling schedule_work() > isn't safe from an NMI. If memory.high is breached from a context where > spinning isn't allowed, use irq_work to schedule the reclaim work. > > Fixes: 3ac4638a734a ("memcg: make memcg_rstat_updated nmi safe") > Signed-off-by: David Stevens This is in mm-unstable and breaks the build for me :) In general - please don't rely on implicit header includes, if you're using functions from a header that's not included, add the include because your local config might happen to import it but another one might be broken. $ make -j $(nproc) LLVM=1 mm/memcontrol.o DESCEND objtool CC arch/x86/kernel/asm-offsets.s UPD include/generated/asm-offsets.h CC kernel/sched/rq-offsets.s UPD include/generated/rq-offsets.h CALL scripts/checksyscalls.sh CC mm/memcontrol.o mm/memcontrol.c:2859:6: error: call to undeclared function 'irq_work_queue'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 2859 | irq_work_queue(&memcg->high_irq_work); | ^ mm/memcontrol.c:4234:2: error: call to undeclared function 'init_irq_work'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 4234 | init_irq_work(&memcg->high_irq_work, high_irq_work_func); | ^ mm/memcontrol.c:4443:2: error: call to undeclared function 'irq_work_sync'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 4443 | irq_work_sync(&memcg->high_irq_work); | ^ 3 errors generated. make[3]: *** [scripts/Makefile.build:290: mm/memcontrol.o] Error 1 make[2]: *** [scripts/Makefile.build:551: mm] Error 2 make[1]: *** [/home/lorenzo/kerndev/kernels/mm/Makefile:2229: .] Error 2 make: *** [Makefile:248: __sub-make] Error 2 > --- > include/linux/memcontrol.h | 1 + > mm/memcontrol.c | 12 +++++++++++- > 2 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 8170bb8066a2..036d973ceca6 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -219,6 +219,7 @@ struct mem_cgroup { > spinlock_t peaks_lock; > > /* Range enforcement for interrupt charges */ > + struct irq_work high_irq_work; > struct work_struct high_work; > > #ifdef CONFIG_ZSWAP > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 6dc4888a90f3..5e2f749067cb 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c You need to add: #include in this file. > @@ -2360,6 +2360,11 @@ static void high_work_func(struct work_struct *work) > reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL); > } > > +static void high_irq_work_func(struct irq_work *work) > +{ > + schedule_work(&container_of(work, struct mem_cgroup, high_irq_work)->high_work); > +} > + > /* > * Clamp the maximum sleep time per allocation batch to 2 seconds. This is > * enough to still cause a significant slowdown in most cases, while still > @@ -2752,7 +2757,10 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, > /* Don't bother a random interrupted task */ > if (!in_task()) { > if (mem_high) { > - schedule_work(&memcg->high_work); > + if (allow_spinning) > + schedule_work(&memcg->high_work); > + else > + irq_work_queue(&memcg->high_irq_work); > break; > } > continue; > @@ -4129,6 +4137,7 @@ static struct mem_cgroup *mem_cgroup_alloc(struct mem_cgroup *parent) > goto fail; > > INIT_WORK(&memcg->high_work, high_work_func); > + init_irq_work(&memcg->high_irq_work, high_irq_work_func); > vmpressure_init(&memcg->vmpressure); > INIT_LIST_HEAD(&memcg->memory_peaks); > INIT_LIST_HEAD(&memcg->swap_peaks); > @@ -4337,6 +4346,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css) > static_branch_dec(&memcg_bpf_enabled_key); > > vmpressure_cleanup(&memcg->vmpressure); > + irq_work_sync(&memcg->high_irq_work); > cancel_work_sync(&memcg->high_work); > memcg1_remove_from_trees(memcg); > free_shrinker_info(memcg); > > base-commit: 8d3ae59288f1e7d58d76558a6ee96d533bc5019f > -- > 2.55.0.897.gb25b4bd76c-goog > > -- Cheers, Lorenzo