From nobody Mon Dec 9 08:06:29 2024 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 9F6B01953BB; Thu, 31 Oct 2024 10:08:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730369341; cv=none; b=auZkuzOfn6AcsIXoKIxqiuoTY92Or4QMaVvR7q6gw0CcJbZsVBKWrSCFTOJSPCi4qr6Pi6Oegl3t/OCPwA9rcQV/z1Z+oQ56BBelYS4GPHQWB4Tp3N4kJuFeoey4p5F8cEn0xlVvG3UA+4jp5uduj5iBDjf7RGhFhOgjdMElX3U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730369341; c=relaxed/simple; bh=0uj3gUEQIA3hXacAoaaRe7lOFrA9PM5P6Lr24r0w6IM=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=OHj5+2Pr9UXERZ2turVLIAPJKV2IdmU4P8Pr3oSmcJxPi0/cRR++eYJwCfROM8y2g0hIQckWA3GaVY/UuQ09T+3QtKID85Toz1Z1H6M07KopWmLDzUe7+Qk28PibPb+RinE6Err8QkleBxkEqW7gURRQQwC/LZn2Ehc1OosFYwM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=WPS5mr4S; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=E9nDvX9X; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="WPS5mr4S"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="E9nDvX9X" Date: Thu, 31 Oct 2024 10:08:57 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1730369338; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RqRlpw2DI6C5paYhFN3Q5eHXvWHI5GVCrorQPaaunuM=; b=WPS5mr4SSzTYY1ni39hoiZUsZRIqB/czD+YW5fIbXQFg5ggqCCV+69BoECWG49nzELsGPJ p3u2zCPaI4YRIiFgRiQCN+fJ5qR3s47/usaffTLGmxm+ewIwcCoo8mXm/U/Eq3QBJIroGw yStyrDWB2yHJ4oiOUCWPk/DHiMMx12gT3UwHNtgbYzRsvuPYUSgrIhjnbIezs3ssSSpjpp VEIcfAt5KsfupgDcH63pzykvnD05Rdp1XIpDJJvoUj40J+D0B7mh/6qeHs8pYdRwgXGlF0 qhaPC7a1whNm7YE0+3+kiAkfYcAT9pLK0ltzu7KWgqGB9bpcZFEMW3E3tTqdZQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1730369338; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RqRlpw2DI6C5paYhFN3Q5eHXvWHI5GVCrorQPaaunuM=; b=E9nDvX9XrpODE/W3Qmf24lTDtRNPSAaiQtmXRoby82H+UexLcjy4/nEWE/q68qH7jcTyCf BPq64CgijS7/itCQ== From: "tip-bot2 for Andrii Nakryiko" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/core] uprobes: allow put_uprobe() from non-sleepable softirq context Cc: Andrii Nakryiko , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20241024044159.3156646-2-andrii@kernel.org> References: <20241024044159.3156646-2-andrii@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <173036933725.3137.3413400151949944467.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the perf/core branch of tip: Commit-ID: 2bf8e5aceff899f5117f14c73e869a61c44d8a69 Gitweb: https://git.kernel.org/tip/2bf8e5aceff899f5117f14c73e869a61c= 44d8a69 Author: Andrii Nakryiko AuthorDate: Wed, 23 Oct 2024 21:41:58 -07:00 Committer: Peter Zijlstra CommitterDate: Wed, 30 Oct 2024 22:42:19 +01:00 uprobes: allow put_uprobe() from non-sleepable softirq context Currently put_uprobe() might trigger mutex_lock()/mutex_unlock(), which makes it unsuitable to be called from more restricted context like softirq. Let's make put_uprobe() agnostic to the context in which it is called, and use work queue to defer the mutex-protected clean up steps. RB tree removal step is also moved into work-deferred callback to avoid potential deadlock between softirq-based timer callback, added in the next patch, and the rest of uprobe code. We can rework locking altogher as a follow up, but that's significantly more tricky, so warrants its own patch set. For now, we need to make sure that changes in the next patch that add timer thread work correctly with existing approach, while concentrating on SRCU + timeout logic. Signed-off-by: Andrii Nakryiko Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20241024044159.3156646-2-andrii@kernel.org --- kernel/events/uprobes.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 4ef4b51..d7e4892 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -27,6 +27,7 @@ #include #include #include +#include =20 #include =20 @@ -61,7 +62,10 @@ struct uprobe { struct list_head pending_list; struct list_head consumers; struct inode *inode; /* Also hold a ref to inode */ - struct rcu_head rcu; + union { + struct rcu_head rcu; + struct work_struct work; + }; loff_t offset; loff_t ref_ctr_offset; unsigned long flags; /* "unsigned long" so bitops work */ @@ -625,10 +629,9 @@ static void uprobe_free_rcu(struct rcu_head *rcu) kfree(uprobe); } =20 -static void put_uprobe(struct uprobe *uprobe) +static void uprobe_free_deferred(struct work_struct *work) { - if (!refcount_dec_and_test(&uprobe->ref)) - return; + struct uprobe *uprobe =3D container_of(work, struct uprobe, work); =20 write_lock(&uprobes_treelock); =20 @@ -652,6 +655,15 @@ static void put_uprobe(struct uprobe *uprobe) call_rcu_tasks_trace(&uprobe->rcu, uprobe_free_rcu); } =20 +static void put_uprobe(struct uprobe *uprobe) +{ + if (!refcount_dec_and_test(&uprobe->ref)) + return; + + INIT_WORK(&uprobe->work, uprobe_free_deferred); + schedule_work(&uprobe->work); +} + static __always_inline int uprobe_cmp(const struct inode *l_inode, const loff_t l_offset, const struct uprobe *r)