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 D8AD03B4EA4; Mon, 3 Aug 2026 21:04:36 +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=1785791078; cv=none; b=ulWCdPTziI4fb5abtewrqPhX2BQ8INMsuvLQ5WyxCD69x0MGP0aB4m93VM2f0+/yA1AW9v0WBWv0BME/vP0dbF+tgEIKVOHKwoK9Zt3ofopXrC1zz9VFW50ZWoeJjfZdCGFFy0PdshsbL4vM0OxHk7ajmtPl0Oq8eYL6mWMU1iA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785791078; c=relaxed/simple; bh=T/MaYaDhfX+oTNtT9EArHi+ETsxEhYGEnKt082Gc0Fw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Dh5quWD4VZpgFLPFKCUbZFqOkleUly8TAlE2Ze+nOYOatdfIoaW5Z2lpXAfvZa++XhoRJ0QjY0L6H5xtQaOFeEcx2Cx2uh+i86eFhG+ZCsIEk6fxazSH0mlKFg2c6x37WkxH0t1SQvXiRaapGk3ZwcSR6ghnIOy1pfU1neBQEhs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GIOK1WlV; 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="GIOK1WlV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 550401F00A3A; Mon, 3 Aug 2026 21:04:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785791076; bh=1wcla+cpyTUwdL1zK44hfxerjucjva9kw2ePOFeXSM0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=GIOK1WlVIGt/41ZD2q3T/RQiNzIQuNgGhlgNzvEzswLomYHzde9u93rIkfLL5JX/y 7GzHGoucFEdkz0BJeJUbM04P1DvjKH8OHbkj7vG3gZ5sKVlXvsrIrBHAQB6QAmZvQZ p/34ljcxbFNUkUrx5rg6eS+bfnkHeIOgJHcUECy0bpl/JPpgeF6PKIHkktZXax19H1 JIv28IRr4WnReW7LWHNlGNgVm68XGiC05AA/sc4vO9v/30UJXPj3f6jmUbeKADlr+H 6xXE3svBtlySxrVKQ5LLT9KXDQwPfohqk/z5iZb7suuP8Kvqu83Zf+58eHUDXKqfnr tCNl85yiN7q1Q== Message-ID: <11a8bf75-8fc1-4d32-a350-6bf8156dd8ab@kernel.org> Date: Mon, 3 Aug 2026 23:04:32 +0200 Precedence: bulk X-Mailing-List: rust-for-linux@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 References: <20260731122826.737703-1-spasswolf@web.de> <20260731192522.GA1014697@ax162> <7c39e6cb-0ccf-4a50-a853-0f6012b05044@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit 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 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