From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794590023; b=rSukLwssvXJpf3Lf7nQ77WvYAnLUSREHIBBBHrNdN21Fw/+elZwmLoyJqIxbcnbwZ7cw YIYY5g3p3bCqYUnAnEEiuFdkgvWa50QuEe4kUgbUpdHQ/LVktQ3t8zNxy0LdMgbNRG6nY 2IlQEsvVLJuE+G59YefQjZSNjNzqtxK/JqVdnTt4+e1oeWPAmB5W2sH7kmemQgv2QdCAf c/TQ2GspZGqisD2JVth5Q612vcD1qeXRl3ADAjf02dYVTaadpLuIcXVn2GBToNLf27hxQ 23zs+rCu+I4+pvAGqFCI8iGZMYeUQz5DVG84I1RFO1TN0fH78O4k1ORpBnDXI1qTCsg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794590023; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=CJo6NM8J98r5cz3Dk5NQesmREp462e1PXmd9mAs7+Eg=; b=2umkk7W6OMo53sBNG1zGrQyImmGdJIjIw2ESuaIxXYD93Vnc7yOachhoXraMsFGqvarM WNAEWbVsFSXx8IE254pReFddSWqq8Byyf95l8nTIS9txiwIPv7vDG0S4dRspLsFzsCbA3 l+HLCTF0stmlWxpAixa66YhmlJV3MVNQbWjgrddxRjDiFgAKkuhQopyHuPu+Jjjd02I9d AseXDb2jxVda6if6kpDOBomcjZWU87SE9NNk4uiu5geESCJtq//6uTDkMm6l4tl6ri9ys B4fW2uGkZlZkW43Map6MZhKNCKFy2svMrfLbKW+OfvNIvcxarzwDNjHFA2wCucbNhcg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=SRsIfBgE; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C086E606A8B2; Fri, 13 Nov 2026 17:13:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=SRsIfBgE Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E09C1F000C4; Fri, 13 Nov 2026 17:13:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794590023; bh=CJo6NM8J98r5cz3Dk5NQesmREp462e1PXmd9mAs7+Eg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SRsIfBgEqDp88S2fojCHEMy+ceNO1vHsxOSW2Q6zROXGLR/uwZtnbk1jjmBQx4fbe Kybo61j6/54Uvz8LjTT/6iUu5tuRNQ8bxl+xO7+xpb8iHi+/gks058myufxI5cKRsp UQpzouIla9UGlTOGUSsPsjBWLcnCy85u4mkfI9YY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.18 046/686] NFSD: Send a meaningful CB_RECALL_ANY keep count Date: Fri, 13 Nov 2026 10:42:59 -0500 Message-ID: <20261113153822.521659509@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153820.902362109@linuxfoundation.org> References: <20261113153820.902362109@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chuck Lever [ Upstream commit 9af39c0773ef956039e1ebe9c235532fe6ee1e50 ] deleg_reaper() sets craa_objects_to_keep to zero on every CB_RECALL_ANY. RFC 8881 Section 20.6.3 defines that field as the number of objects the client may keep, leaving the client to choose which of the excess to return, because the server cannot read lack of recent use as lack of usefulness. Zero asks for every delegation the client holds, including the ones backing files an application still has open. There is also no reason NFSD has to reclaim the entire delegation working set on the first sign of memory pressure. Derive the keep count from cl_deleg_count so that each callback asks for one delegation. Both the shrinker and the laundromat re-arm while their condition lasts, so a client with more to give is asked again on the next pass. The Linux client ignores craa_objects_to_keep and returns unused delegations selected from the type mask alone, so the count changes nothing for it. Fixes: 44df6f439a17 ("NFSD: add delegation reaper to react to low memory condition") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260817-recall-any-keep-count-v5-4-3b2cffce701e@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4state.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 222f2aadaafad..44ca5746911c8 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -7306,6 +7306,7 @@ deleg_reaper(struct nfsd_net *nn) { struct list_head *pos, *next; struct nfs4_client *clp; + unsigned int count; spin_lock(&nn->client_lock); list_for_each_safe(pos, next, &nn->client_lru) { @@ -7315,21 +7316,33 @@ deleg_reaper(struct nfsd_net *nn) continue; if (clp->cl_state != NFSD4_ACTIVE) continue; - if (list_empty(&clp->cl_delegations)) - continue; if (atomic_read(&clp->cl_delegs_in_recall)) continue; if (ktime_get_boottime_seconds() - clp->cl_ra_time < 5) continue; if (clp->cl_cb_state != NFSD4_CB_UP) continue; + /* + * This read races with hash_delegation_locked() and + * unhash_delegation_locked() on other CPUs. A stale + * count only skews the keep value; the next + * laundromat pass sees a more current one. + */ + count = data_race(READ_ONCE(clp->cl_deleg_count)); + if (!count) + continue; if (test_and_set_bit(NFSD4_CALLBACK_RUNNING, &clp->cl_ra->ra_cb.cb_flags)) continue; /* release in nfsd4_cb_recall_any_release */ kref_get(&clp->cl_nfsdfs.cl_ref); clp->cl_ra_time = ktime_get_boottime_seconds(); - clp->cl_ra->ra_keep = 0; + /* + * Ask for a single delegation. Recalling one before it + * is needed costs the client an OPEN when it next + * touches the file. + */ + clp->cl_ra->ra_keep = count - 1; clp->cl_ra->ra_bmval[0] = BIT(RCA4_TYPE_MASK_RDATA_DLG) | BIT(RCA4_TYPE_MASK_WDATA_DLG); trace_nfsd_cb_recall_any(clp->cl_ra); -- 2.53.0