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 9BAF84B7145 for ; Thu, 3 Sep 2026 14:30:53 +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=1788445865; cv=none; b=a5v+fbbs9NrWo9llwloCaXLCQ2P+BxZevcOZMrFjqfonlJc5LbEQ/sc51BUfve5pVlPEODbNlESmaLGEqvs/j5VMPUY6G5wwArAplC8iuEW51+bSmjDoDxjZ3vV982PE7rGVu6vFyjy8qhmMEFf6Y7Cyqlka5E/T1RHSnbOZ4s4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788445865; c=relaxed/simple; bh=cNXel8zTIxdGFagimRrens4DbCDKukV2JdEiQAc1woY=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=STq2iQ+GyRhMPsAm1D+2uGNqAwYeLc+CB0ISufdMwwgmRrqdjS7nBuIhjIKsur9LgAtKmY3VV/I/p9VL36ItD1rik0hbTzpsSzF1CJ9/2RC/GRdW2sBGPUd8r9huNW7xEV3BReGGAasKRzKtQgMoandWxG1P7pcmHyu7+Tgka+g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xOGqoTki; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xOGqoTki" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00DB91F00A3E; Thu, 3 Sep 2026 14:30:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788445852; bh=zD8QtmfZWDTRnCMSHVheADF/zGCXlxkJgiodPrRpyB4=; h=Subject:To:Cc:From:Date; b=xOGqoTkiDI307dO7t+3KYIAHoXNz14qUx9B5d4UTiLEmlof20rPgXcqW4kRknwL1m A7ztbWxGAardzVLSV2wMXWzFH0wuXuikLz3LJ2WFA8YSno99fxU9F7Si4/H3zscjJ0 rVkjccoz8EKlbsiIztBl1rUqvYQwSfiZ2cbbwnhM= Subject: FAILED: patch "[PATCH] rpcrdma: arm rn_done before publishing the notification" failed to apply to 6.12-stable tree To: cel@kernel.org,chuck.lever@oracle.com Cc: From: Date: Thu, 03 Sep 2026 16:08:59 +0200 Message-ID: <2026090359-consensus-citizen-be20@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 5b06f706374c37375bdff9d21cc10e61df925a92 # git commit -s git send-email --to '' --in-reply-to '2026090359-consensus-citizen-be20@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 5b06f706374c37375bdff9d21cc10e61df925a92 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Mon, 1 Jun 2026 16:17:03 -0400 Subject: [PATCH] rpcrdma: arm rn_done before publishing the notification rpcrdma_rn_register() inserts @rn into rd_xa with xa_alloc() before storing the caller's callback in rn->rn_done. The xarray makes @rn reachable to rpcrdma_remove_one(), which walks rd_xa and invokes rn->rn_done(rn) for every registered notification. A device removal that races a fresh registration can therefore observe @rn with rn_done still NULL, because the notification objects are zero allocated by their owners, and call through a NULL function pointer. Store rn->rn_done before xa_alloc() publishes @rn. The xarray's store-side and load-side ordering then guarantees that any CPU which finds @rn in rd_xa also observes the armed callback. rpcrdma_rn_unregister() treats a non-NULL rn_done as the sentinel for a completed registration, so the early store must not survive a failed registration. Clear rn_done again when xa_alloc() fails. Were it left set, the failed-accept cleanup path would call rpcrdma_rn_unregister() on an @rn that was never inserted, erasing an unrelated rd_xa slot and underflowing rd_kref. Fixes: 7e86845a0346 ("rpcrdma: Implement generic device removal") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260601201703.46078-1-cel@kernel.org Signed-off-by: Chuck Lever diff --git a/net/sunrpc/xprtrdma/ib_client.c b/net/sunrpc/xprtrdma/ib_client.c index 69166d5d9987..188f7a13397f 100644 --- a/net/sunrpc/xprtrdma/ib_client.c +++ b/net/sunrpc/xprtrdma/ib_client.c @@ -52,8 +52,8 @@ static struct rpcrdma_device *rpcrdma_get_client_data(struct ib_device *device) * is unregistered first. * * On failure, a negative errno is returned. rn->rn_done is left - * NULL on every failure path (it is assigned only after xa_alloc - * and kref_get have both succeeded), so the @rn may safely be + * NULL on every failure path (it is armed before xa_alloc but + * cleared again if xa_alloc fails), so the @rn may safely be * passed to rpcrdma_rn_unregister() without a separate * registered/unregistered flag in the caller. */ @@ -66,10 +66,21 @@ int rpcrdma_rn_register(struct ib_device *device, if (!rd || test_bit(RPCRDMA_RD_F_REMOVING, &rd->rd_flags)) return -ENETUNREACH; - if (xa_alloc(&rd->rd_xa, &rn->rn_index, rn, xa_limit_32b, GFP_KERNEL) < 0) - return -ENOMEM; - kref_get(&rd->rd_kref); + /* + * Arm rn_done before xa_alloc() publishes @rn: once @rn is + * visible in rd_xa, a concurrent rpcrdma_remove_one() can + * call rn->rn_done(), so the pointer must already be set. + * + * Restore NULL if xa_alloc() fails. rn_done doubles as the + * registration sentinel for rpcrdma_rn_unregister(); a stale + * value would unregister an @rn that was never inserted. + */ rn->rn_done = done; + if (xa_alloc(&rd->rd_xa, &rn->rn_index, rn, xa_limit_32b, GFP_KERNEL) < 0) { + rn->rn_done = NULL; + return -ENOMEM; + } + kref_get(&rd->rd_kref); trace_rpcrdma_client_register(device, rn); return 0; } @@ -102,8 +113,9 @@ void rpcrdma_rn_unregister(struct ib_device *device, /* * rn_done is the registration sentinel: rpcrdma_rn_register - * assigns it last, after xa_alloc and kref_get have both - * succeeded. A NULL rn_done means this notification was + * leaves it NULL on every failure path, clearing it again if + * xa_alloc fails, so a non-NULL rn_done marks a completed + * registration. A NULL rn_done means this notification was * never registered (or its registration failed) or has * already been unregistered, and the call is a no-op. * Without this guard, rn_index == 0 from a kzalloc'd