From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 65A664446EA; Tue, 4 Aug 2026 10:35:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785839748; cv=none; b=MQqHzKlJahpcapTBBrvfImOQSKCn/XiUlLxOLe1Oo0c+N4F0Lk6CGrIPmSswFkCyzKkfqMystmrCZ59dTsuUc2RmDLRsoSWDrmhQwkdR5+ftfE0jIQ20gx6sOQ2Q0DJuRJyK9SQuxbPmpbbzk8YWPZ2l0lcwGnIHw5esrrQp3OU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785839748; c=relaxed/simple; bh=e71vPC77gj6gAv8DhE4ZznJ/hxieNPyUeDo98rW2PZI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kzl9sQwMQfj698Oe0g1QwizFmKWeNgOBWTCNpOnNDanay5I3oLjluR1Gzk38upQw/J1A1D+DxydZ0eAFS8a6EvTgz2deGWMxmXHWiXSril6B4R+Yx3VX9QGzpNr70uNoXuMF9vftnc/h2oVXmC3xUtREmZPulrNkMnf2mbDOkHU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lVWRqRSl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lVWRqRSl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DE311F000E9; Tue, 4 Aug 2026 10:35:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785839746; bh=Fsy6Tb63CU1Ad3Kp3knM6xPa/jSSeaOo1zveF5t3YuM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=lVWRqRSlWbCrpYE1cx/LysJJuWXC3nwwY5FHDuKT6a6lfzdDrwrsB0jjMTMyQcBkC o70HU6H0nFr5JqmOHvHjdQW42f9OxUrzH/IsB/EyvvazYKoEZ5vwIOTjYADS4fc3yj lAT9GOEfGi68GVguMRJhSyRZwS3JUVbeAjq2IBQUuKgD1HVKIFVFqHAw1UQ0K8xQev I6nefBOfohdB8xKrrgTpLY4klyP5G6Ph0IeOQrXh/Ju5t9kC06Pz4KIdjoBn+S2lwA J0oWjfQUxPfOqPg5NL+Bo9x+biV+0z30e+QRf9OecM2gQ5z6zLcumuc9P+8b5HZoea 35l0BFpklzISw== Message-ID: <7189ebb5-ae48-4466-9055-1ab1b0b5ef7c@kernel.org> Date: Tue, 4 Aug 2026 12:35:42 +0200 Precedence: bulk X-Mailing-List: linux-next@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: rust compile failure in next-20260730 Content-Language: en-US To: Gary Guo , Boqun Feng Cc: Nathan Chancellor , Bert Karwatzki , Harry Yoo , linux-kernel@vger.kernel.org, linux-next@vger.kernel.org, Alice Ryhl , Greg Kroah-Hartman , rust-for-linux@vger.kernel.org, Miguel Ojeda , Mark Brown References: <20260731122826.737703-1-spasswolf@web.de> <20260731192522.GA1014697@ax162> <7c39e6cb-0ccf-4a50-a853-0f6012b05044@kernel.org> <11a8bf75-8fc1-4d32-a350-6bf8156dd8ab@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/4/26 12:10, Gary Guo wrote: > On Mon Aug 3, 2026 at 10:04 PM BST, Vlastimil Babka (SUSE) wrote: >> On 8/3/26 17:32, Gary Guo wrote: >>> On Mon Aug 3, 2026 at 4:10 PM BST, Vlastimil Babka (SUSE) wrote: >>>> On 8/3/26 16:23, Boqun Feng wrote: >>>>> On Mon, Aug 03, 2026 at 02:57:49PM +0100, Gary Guo wrote: >>>>>> >>>>>> We could also unconditionally use `kvfree_rcu_head` here, and >>>>>> add >>>>>> >>>>>> #[cfg(not(CONFIG_KVFREE_RCU_BATCHED))] >>>>>> pub type kvfree_rcu_head = callback_head; >>>>>> >>>>>> to bindings.rs? >>>>>> >>>>> >>>>> This option is currently not maintainable unless it becomes a >>>>> maintainer-aware way to handle things like this. >>>>> >>>>>> (Or even better, changing `#define` to `typedef` so bindgen takes care of >>>>>> everything). >>>>>> >>>>> >>>>> Yes, this is better IMO, but it's up to slab maintainers. :-) >>>> >>>> Can you elaborate a bit please, how would that look like? >>> >>> I was thinking of doing `typedef struct rcu_head kvfree_rcu_head;` but of course >>> that didn't work because you can't use typedef to create `kvfree_rcu_head` :) >>> >>> However, something like this could work? >>> >>> #ifdef CONFIG_KVFREE_RCU_BATCHED >>> ... >>> #else >>> struct kvfree_rcu_head { >>> struct rcu_head head; >>> }; >>> #endif >>> >>> and everywhere add a cast everywhere that expects kvfree_rcu_head == rcu_head. >>> >>> but this would indeed be more complex :( >> >> So you mean like this? Doesn't seem so complex and seems to compile here >> with CONFIG_KVFREE_RCU_BATCHED both disabled and enabled. > > I thought that a lot more places have to be updated, but it looks from your diff > below that this is simple enough. Thanks. The slab/for-next branch now includes the slab changes. The merge commit should thus perform the rust/kernel/sync/poll.rs change. > Best, > Gary > >> I can apply the slab part in slab tree, but AFAICS the poll.rs >> change still needs to be done in the merge commit. Unless there's >> some way to make things conditional on whether kvfree_rcu_head exists? >> >> diff --git a/include/linux/types.h b/include/linux/types.h >> index 79bf419c69e4..53e0adca4b9f 100644 >> --- a/include/linux/types.h >> +++ b/include/linux/types.h >> @@ -262,7 +262,9 @@ struct kvfree_rcu_head { >> struct kvfree_rcu_head *next; >> }; >> #else >> -#define kvfree_rcu_head rcu_head >> +struct kvfree_rcu_head { >> + struct rcu_head head; >> +}; >> #endif >> >> typedef void (*rcu_callback_t)(struct rcu_head *head); >> diff --git a/mm/slab_common.c b/mm/slab_common.c >> index 64845ac81b79..aecbe9b9df4c 100644 >> --- a/mm/slab_common.c >> +++ b/mm/slab_common.c >> @@ -1325,11 +1325,11 @@ EXPORT_SYMBOL_GPL(kfree_call_rcu_nolock); >> >> #ifndef CONFIG_KVFREE_RCU_BATCHED >> >> -void kvfree_call_rcu(struct rcu_head *head, void *ptr) >> +void kvfree_call_rcu(struct kvfree_rcu_head *head, void *ptr) >> { >> if (head) { >> kasan_record_aux_stack(ptr); >> - call_rcu(head, kvfree_rcu_cb); >> + call_rcu(&head->head, kvfree_rcu_cb); >> return; >> } >> >> diff --git a/rust/kernel/sync/poll.rs b/rust/kernel/sync/poll.rs >> index 684dfa242b1a..f3cdf95db12d 100644 >> --- a/rust/kernel/sync/poll.rs >> +++ b/rust/kernel/sync/poll.rs >> @@ -124,7 +124,7 @@ pub struct PollCondVarBox { >> struct PollCondVarBoxInner { >> #[pin] >> inner: PollCondVar, >> - rcu: Opaque, >> + rcu: Opaque, >> } >> >> // SAFETY: PollCondVar is Send > >