From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E67FA221DB1; Mon, 2 Jun 2025 15:17:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748877457; cv=none; b=amObSbZJwHME0mZ+aGMjHfEf8THdxPxgfSJp5JElvsxusE1qSow/aP44hB6FmBNWcd9a+oGpOU9ZerOQEP4+e/nlBIkYNQTgCgPVFmfznEQOEc2qxrd1rECDgv9M6EygFnSVdSJGjWyKTMsNVrjNmCldvpjkvxiBt3Y65d7weNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748877457; c=relaxed/simple; bh=ZENF+OqbrAai3e0Zp9Vn6xr3v8i7SIqPCzcCis5KzAs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eoEtCAdKg4fhCV+aA+t0C3JwWFVJ88zxOY4HDXM84PVF2X154Fj8/TWlbRxxBhCvgWQmWfgASN2RxIcPINKlEBDzSEvnNEWdirFM0U9Slwa2iL2Ai7aROI4UfnkAHv/3TdEAUnF5hndcSSzmSDT8ZEBqnXj6N/fSya2qeLBi+9w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=froMkeeJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="froMkeeJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50331C4CEEB; Mon, 2 Jun 2025 15:17:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1748877456; bh=ZENF+OqbrAai3e0Zp9Vn6xr3v8i7SIqPCzcCis5KzAs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=froMkeeJi2QjdcF+kW1Me5K/CHa7jEL9QnyNZAgNhT18DDNd4C8OggFMfHL+fdjrE Ndue3vHAj1l99x9Es/PDXJa6Dhil5r9GlUxbbM/XVbfMUoDa80nGlkKwYtsdJiEueM FHBqn2YEMV33xIwLf+rH4OXqkU73RDHSbJhBEg0Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Jakub Kicinski , Lee Jones Subject: [PATCH 6.1 284/325] af_unix: Try to run GC async. Date: Mon, 2 Jun 2025 15:49:20 +0200 Message-ID: <20250602134331.299499705@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250602134319.723650984@linuxfoundation.org> References: <20250602134319.723650984@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima commit d9f21b3613337b55cc9d4a6ead484dca68475143 upstream. If more than 16000 inflight AF_UNIX sockets exist and the garbage collector is not running, unix_(dgram|stream)_sendmsg() call unix_gc(). Also, they wait for unix_gc() to complete. In unix_gc(), all inflight AF_UNIX sockets are traversed at least once, and more if they are the GC candidate. Thus, sendmsg() significantly slows down with too many inflight AF_UNIX sockets. However, if a process sends data with no AF_UNIX FD, the sendmsg() call does not need to wait for GC. After this change, only the process that meets the condition below will be blocked under such a situation. 1) cmsg contains AF_UNIX socket 2) more than 32 AF_UNIX sent by the same user are still inflight Note that even a sendmsg() call that does not meet the condition but has AF_UNIX FD will be blocked later in unix_scm_to_skb() by the spinlock, but we allow that as a bonus for sane users. The results below are the time spent in unix_dgram_sendmsg() sending 1 byte of data with no FD 4096 times on a host where 32K inflight AF_UNIX sockets exist. Without series: the sane sendmsg() needs to wait gc unreasonably. $ sudo /usr/share/bcc/tools/funclatency -p 11165 unix_dgram_sendmsg Tracing 1 functions for "unix_dgram_sendmsg"... Hit Ctrl-C to end. ^C nsecs : count distribution [...] 524288 -> 1048575 : 0 | | 1048576 -> 2097151 : 3881 |****************************************| 2097152 -> 4194303 : 214 |** | 4194304 -> 8388607 : 1 | | avg = 1825567 nsecs, total: 7477526027 nsecs, count: 4096 With series: the sane sendmsg() can finish much faster. $ sudo /usr/share/bcc/tools/funclatency -p 8702 unix_dgram_sendmsg Tracing 1 functions for "unix_dgram_sendmsg"... Hit Ctrl-C to end. ^C nsecs : count distribution [...] 128 -> 255 : 0 | | 256 -> 511 : 4092 |****************************************| 512 -> 1023 : 2 | | 1024 -> 2047 : 0 | | 2048 -> 4095 : 0 | | 4096 -> 8191 : 1 | | 8192 -> 16383 : 1 | | avg = 410 nsecs, total: 1680510 nsecs, count: 4096 Signed-off-by: Kuniyuki Iwashima Link: https://lore.kernel.org/r/20240123170856.41348-6-kuniyu@amazon.com Signed-off-by: Jakub Kicinski Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman --- include/net/af_unix.h | 12 ++++++++++-- include/net/scm.h | 1 + net/core/scm.c | 5 +++++ net/unix/af_unix.c | 6 ++++-- net/unix/garbage.c | 10 +++++++++- 5 files changed, 29 insertions(+), 5 deletions(-) --- a/include/net/af_unix.h +++ b/include/net/af_unix.h @@ -8,12 +8,20 @@ #include #include +#if IS_ENABLED(CONFIG_UNIX) +struct unix_sock *unix_get_socket(struct file *filp); +#else +static inline struct unix_sock *unix_get_socket(struct file *filp) +{ + return NULL; +} +#endif + void unix_inflight(struct user_struct *user, struct file *fp); void unix_notinflight(struct user_struct *user, struct file *fp); void unix_destruct_scm(struct sk_buff *skb); void unix_gc(void); -void wait_for_unix_gc(void); -struct unix_sock *unix_get_socket(struct file *filp); +void wait_for_unix_gc(struct scm_fp_list *fpl); struct sock *unix_peer_get(struct sock *sk); #define UNIX_HASH_MOD (256 - 1) --- a/include/net/scm.h +++ b/include/net/scm.h @@ -23,6 +23,7 @@ struct scm_creds { struct scm_fp_list { short count; + short count_unix; short max; struct user_struct *user; struct file *fp[SCM_MAX_FD]; --- a/net/core/scm.c +++ b/net/core/scm.c @@ -36,6 +36,7 @@ #include #include #include +#include /* @@ -85,6 +86,7 @@ static int scm_fp_copy(struct cmsghdr *c return -ENOMEM; *fplp = fpl; fpl->count = 0; + fpl->count_unix = 0; fpl->max = SCM_MAX_FD; fpl->user = NULL; } @@ -109,6 +111,9 @@ static int scm_fp_copy(struct cmsghdr *c fput(file); return -EINVAL; } + if (unix_get_socket(file)) + fpl->count_unix++; + *fpp++ = file; fpl->count++; } --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1875,11 +1875,12 @@ static int unix_dgram_sendmsg(struct soc long timeo; int err; - wait_for_unix_gc(); err = scm_send(sock, msg, &scm, false); if (err < 0) return err; + wait_for_unix_gc(scm.fp); + err = -EOPNOTSUPP; if (msg->msg_flags&MSG_OOB) goto out; @@ -2145,11 +2146,12 @@ static int unix_stream_sendmsg(struct so bool fds_sent = false; int data_len; - wait_for_unix_gc(); err = scm_send(sock, msg, &scm, false); if (err < 0) return err; + wait_for_unix_gc(scm.fp); + err = -EOPNOTSUPP; if (msg->msg_flags & MSG_OOB) { #if IS_ENABLED(CONFIG_AF_UNIX_OOB) --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -335,8 +335,9 @@ void unix_gc(void) } #define UNIX_INFLIGHT_TRIGGER_GC 16000 +#define UNIX_INFLIGHT_SANE_USER (SCM_MAX_FD * 8) -void wait_for_unix_gc(void) +void wait_for_unix_gc(struct scm_fp_list *fpl) { /* If number of inflight sockets is insane, * force a garbage collect right now. @@ -348,6 +349,13 @@ void wait_for_unix_gc(void) !READ_ONCE(gc_in_progress)) unix_gc(); + /* Penalise users who want to send AF_UNIX sockets + * but whose sockets have not been received yet. + */ + if (!fpl || !fpl->count_unix || + READ_ONCE(fpl->user->unix_inflight) < UNIX_INFLIGHT_SANE_USER) + return; + if (READ_ONCE(gc_in_progress)) flush_work(&unix_gc_work); }