From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B1EF35DA5D; Mon, 22 Jun 2026 06:16:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782108981; cv=none; b=lfesxdaTZcQ+VZ1jzsbEZTiiKg+WqNJXvPSsI7vatbgFjaNue3R/y2LJBhy5UEw+oBChnI3gyYChvCyYizPD0NKlBr2DMm/+G7lqv5YtEIPKvCcDh6JJwkEwpVSKHzFw4GZYoUeDVXncergJITKsOHJerDEzNbqaZ0D1HX0hweQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782108981; c=relaxed/simple; bh=hk8s1HyY3dzHKU/LGLjDjlXFo8lRWPfUJ+Vkj0iR3dk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F1ggR9CTuEuGVyTuf9KE1/GpZM0RPl0Knr+KdqWSBado0xvY9SUiJXosvYsSgYIB/dxltiKldZ5Tj/cKoSI3YhXdEnlzaz/N71tPKr5n6w+HtKRtarvoe15z4zBg8ZhG3DUxT0pa9V1wtV3G4adepCRLb17CIDGyiJIsVYuOmyg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=t15fr1vS; arc=none smtp.client-ip=91.218.175.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="t15fr1vS" Message-ID: <8c8f1849-86d3-4c69-be27-30bbdffdf616@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782108966; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uc01vIZYGfTIV3fdEG67Z2UKVAOKK7e6urfcQoWTPXs=; b=t15fr1vSWPqYuOVx1/bxMEqBYsgHtm0lD1qKuOgL6xYl94f+kJLWMkDtNXA1O6oXS4NWrk UXfi4I4xGSapixdXs6K5v7yl7QxZTsj0xBO+b54oW8Z9JaKuiK5OobLxhWf+TcWH/AL++5 EurPaDWOivYCOI4YE0QW4UrJN1dv49Y= Date: Mon, 22 Jun 2026 14:15:01 +0800 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v3 0/7] Prepare mutable list iterators to cache cursor state To: Alexei Starovoitov Cc: Andrew Morton , David Hildenbrand , Jens Axboe , Tejun Heo , Alexander Viro , Christian Brauner , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Johannes Weiner , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Juri Lelli , Vincent Guittot , Paul Moore , Andy Shevchenko , "Paul E. McKenney" , Shakeel Butt , =?UTF-8?Q?Christian_K=C3=B6nig?= , David Howells , Simona Vetter , Randy Dunlap , Luca Ceresoli , Philipp Stanner , linux-block@vger.kernel.org, LKML , "open list:CONTROL GROUP (CGROUP)" , linux-ntfs-dev@lists.sourceforge.net, Linux-Fsdevel , io-uring , audit@vger.kernel.org, bpf , Network Development , dri-devel@lists.freedesktop.org, "linux-perf-use." , linux-trace-kernel , kexec@lists.infradead.org, live-patching@vger.kernel.org, linux-modules@vger.kernel.org, Linux Crypto Mailing List , Linux Power Management , rcu@vger.kernel.org, sched-ext@lists.linux.dev, linux-mm , virtualization@lists.linux.dev, damon@lists.linux.dev, clang-built-linux , chengkaitao , Muchun Song References: <20260622040533.29824-1-kaitao.cheng@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Kaitao Cheng In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 在 2026/6/22 13:28, Alexei Starovoitov 写道: > On Sun, Jun 21, 2026 at 9:06 PM Kaitao Cheng wrote: >> >> From: chengkaitao >> >> The list_for_each*_safe() helpers are used when the loop body may remove >> the current entry. Their current interface, however, forces every caller >> to define a temporary cursor outside the macro and pass it in, even when >> the caller never uses that cursor directly. For most call sites this >> extra cursor is just boilerplate required by the macro implementation. >> >> This is awkward because the saved next pointer is an internal detail of >> the iteration. Callers that only remove or move the current entry do not >> need to spell it out. >> >> The _safe() suffix has also caused confusion. Christian Koenig pointed >> out that the name is easy to read as a thread-safe variant, especially >> for beginners, even though it only means that the iterator keeps enough >> state to tolerate removal of the current entry. He suggested _mutable() >> as a clearer description of what the loop permits. >> >> Add *_mutable() iterator variants for list, hlist and llist. The new >> helpers are variadic and support both forms. In the common case, the >> caller omits the temporary cursor and the macro creates a unique internal >> cursor with typeof(pos) and __UNIQUE_ID(). If a loop really needs an >> explicit temporary cursor, the caller can still pass it and the helper >> keeps the existing *_safe() behaviour. >> >> For example, a call site may use the shorter form: >> >> list_for_each_entry_mutable(pos, head, member) >> >> or keep the explicit temporary cursor form: >> >> list_for_each_entry_mutable(pos, tmp, head, member) >> >> The existing *_safe() helpers remain available for compatibility. This >> series only converts users in mm, block, kernel, init and io_uring. If >> this approach looks acceptable, the remaining users can be converted in >> follow-up series. >> >> Changes in v3 (Christian König, Andy Shevchenko): >> - Convert safe list walks to mutable iterators >> >> Changes in v2 (Muchun Song, Andy Shevchenko): >> - Drop the list_for_each_entry_mutable*() helpers from v1 and make the >> cursor change directly in the existing list_for_each_entry*() helpers. >> - Open-code special list walks that rely on updating the loop cursor in >> the body, preserving their existing traversal semantics. >> >> Link to v2: >> https://lore.kernel.org/all/20260609061347.93688-1-kaitao.cheng@linux.dev/ >> >> Link to v1: >> https://lore.kernel.org/all/20260529082149.76764-1-kaitao.cheng@linux.dev/ >> >> Kaitao Cheng (7): >> list: Add mutable iterator variants >> llist: Add mutable iterator variants >> mm: Use mutable list iterators >> block: Use mutable list iterators >> kernel: Use mutable list iterators >> initramfs: Use mutable list iterator >> io_uring: Use mutable list iterators >> >> block/bfq-iosched.c | 17 +- >> block/blk-cgroup.c | 12 +- >> block/blk-flush.c | 4 +- >> block/blk-iocost.c | 18 +- >> block/blk-mq.c | 8 +- >> block/blk-throttle.c | 4 +- >> block/kyber-iosched.c | 4 +- >> block/partitions/ldm.c | 8 +- >> block/sed-opal.c | 4 +- >> include/linux/list.h | 269 ++++++++++++++++++++++++---- >> include/linux/llist.h | 81 +++++++-- >> init/initramfs.c | 5 +- >> io_uring/cancel.c | 6 +- >> io_uring/poll.c | 3 +- >> io_uring/rw.c | 4 +- >> io_uring/timeout.c | 8 +- >> io_uring/uring_cmd.c | 3 +- >> kernel/audit_tree.c | 4 +- >> kernel/audit_watch.c | 16 +- >> kernel/auditfilter.c | 4 +- >> kernel/auditsc.c | 4 +- >> kernel/bpf/arena.c | 10 +- >> kernel/bpf/arraymap.c | 8 +- >> kernel/bpf/bpf_local_storage.c | 3 +- >> kernel/bpf/bpf_lru_list.c | 25 ++- >> kernel/bpf/btf.c | 18 +- >> kernel/bpf/cgroup.c | 7 +- >> kernel/bpf/cpumap.c | 4 +- >> kernel/bpf/devmap.c | 10 +- >> kernel/bpf/helpers.c | 8 +- >> kernel/bpf/local_storage.c | 4 +- >> kernel/bpf/memalloc.c | 16 +- >> kernel/bpf/offload.c | 8 +- >> kernel/bpf/states.c | 4 +- >> kernel/bpf/stream.c | 4 +- >> kernel/bpf/verifier.c | 6 +- >> kernel/cgroup/cgroup-v1.c | 4 +- >> kernel/cgroup/cgroup.c | 54 +++--- >> kernel/cgroup/dmem.c | 12 +- >> kernel/cgroup/rdma.c | 8 +- >> kernel/events/core.c | 44 +++-- >> kernel/events/uprobes.c | 12 +- >> kernel/exit.c | 8 +- >> kernel/fail_function.c | 4 +- >> kernel/gcov/clang.c | 4 +- >> kernel/irq_work.c | 4 +- >> kernel/kexec_core.c | 4 +- >> kernel/kprobes.c | 16 +- >> kernel/livepatch/core.c | 4 +- >> kernel/livepatch/core.h | 4 +- >> kernel/liveupdate/kho_block.c | 4 +- >> kernel/liveupdate/luo_flb.c | 4 +- >> kernel/locking/rwsem.c | 2 +- >> kernel/locking/test-ww_mutex.c | 2 +- >> kernel/module/main.c | 11 +- >> kernel/padata.c | 4 +- >> kernel/power/snapshot.c | 8 +- >> kernel/power/wakelock.c | 4 +- >> kernel/printk/printk.c | 11 +- >> kernel/ptrace.c | 4 +- >> kernel/rcu/rcutorture.c | 3 +- >> kernel/rcu/tasks.h | 9 +- >> kernel/rcu/tree.c | 6 +- >> kernel/resource.c | 4 +- >> kernel/sched/core.c | 4 +- >> kernel/sched/ext.c | 22 +-- >> kernel/sched/fair.c | 28 +-- >> kernel/sched/topology.c | 4 +- >> kernel/sched/wait.c | 4 +- >> kernel/seccomp.c | 4 +- >> kernel/signal.c | 11 +- >> kernel/smp.c | 4 +- >> kernel/taskstats.c | 8 +- >> kernel/time/clockevents.c | 6 +- >> kernel/time/clocksource.c | 4 +- >> kernel/time/posix-cpu-timers.c | 4 +- >> kernel/time/posix-timers.c | 3 +- >> kernel/torture.c | 3 +- >> kernel/trace/bpf_trace.c | 4 +- >> kernel/trace/ftrace.c | 49 +++-- >> kernel/trace/ring_buffer.c | 25 ++- >> kernel/trace/trace.c | 12 +- >> kernel/trace/trace_dynevent.c | 6 +- >> kernel/trace/trace_dynevent.h | 5 +- >> kernel/trace/trace_events.c | 35 ++-- >> kernel/trace/trace_events_filter.c | 4 +- >> kernel/trace/trace_events_hist.c | 8 +- >> kernel/trace/trace_events_trigger.c | 17 +- >> kernel/trace/trace_events_user.c | 16 +- >> kernel/trace/trace_stat.c | 4 +- >> kernel/user-return-notifier.c | 3 +- >> kernel/workqueue.c | 16 +- >> mm/backing-dev.c | 8 +- >> mm/balloon.c | 8 +- >> mm/cma.c | 4 +- >> mm/compaction.c | 4 +- >> mm/damon/core.c | 4 +- >> mm/damon/sysfs-schemes.c | 4 +- >> mm/dmapool.c | 4 +- >> mm/huge_memory.c | 8 +- >> mm/hugetlb.c | 56 +++--- >> mm/hugetlb_vmemmap.c | 16 +- >> mm/khugepaged.c | 14 +- >> mm/kmemleak.c | 7 +- >> mm/ksm.c | 25 +-- >> mm/list_lru.c | 4 +- >> mm/memcontrol-v1.c | 8 +- >> mm/memory-failure.c | 12 +- >> mm/memory-tiers.c | 4 +- >> mm/migrate.c | 23 ++- >> mm/mmu_notifier.c | 9 +- >> mm/page_alloc.c | 8 +- >> mm/page_reporting.c | 2 +- >> mm/percpu.c | 11 +- >> mm/pgtable-generic.c | 4 +- >> mm/rmap.c | 10 +- >> mm/shmem.c | 9 +- >> mm/slab_common.c | 14 +- >> mm/slub.c | 33 ++-- >> mm/swapfile.c | 4 +- >> mm/userfaultfd.c | 12 +- >> mm/vmalloc.c | 24 +-- >> mm/vmscan.c | 7 +- >> mm/zsmalloc.c | 4 +- >> 124 files changed, 875 insertions(+), 681 deletions(-) > > Not sure what you were thinking, but this diff stat > is not landable. [PATCH v3 1/7] and [PATCH v3 2/7] contain the main logic and can be merged directly. They are also compatible with the old API. [PATCH v3 3/7] through [PATCH v3 7/7] are just simple interface replacements and do not change any functional logic. They can be left unmerged for now; individual modules can pick them up later if needed. In v2, Andy Shevchenko mentioned: "If it's done by Linus himself during the day when he prepares -rc1, it's fine." Even so, the changes in this patch series are indeed quite large and touch almost every subsystem. I have only converted part of them for now, so I wanted to send this out first and see what people think. -- Thanks Kaitao Cheng