From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yx1-f42.google.com (mail-yx1-f42.google.com [74.125.224.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 551FB3B8D67 for ; Fri, 12 Dec 2025 05:15:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.224.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765516552; cv=none; b=H0jOvEW6D4WLBT08VPDeb4YI/luYGSH4MJNHbjgNfHwnxCiUiG06zeTluR6MnRGa+CCqgcw00Li02xkMd+hHZ1nPSNDjUwJZ4ussIVUdlmOGhgqbfWp2i3r535maFtwmpWtuPFuP+OaAhbYyUtohnFm/WDmT4Z8d93EVO6+n4EM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765516552; c=relaxed/simple; bh=P/4fHit3XUT8QBZzqwt0uv/JBee16RdfMfdfYXcg910=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=X0f3uIDUuVSP3+sPVZGdFB6GlTzNcsOPe8UTVgPDRoOwPa9mYyUbjYuhZpVIeAVKHIYSURRR9G9tPp2lVQwZaCt77xLRwUuHeFxFZSnQL/8Acw/gKeSrurgRzgfJkbDKJUcgiQ0Y/Z9ONxb80l4TvhVzQGJnHYwkQ99IEeWQH9U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=AR679X4L; arc=none smtp.client-ip=74.125.224.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="AR679X4L" Received: by mail-yx1-f42.google.com with SMTP id 956f58d0204a3-64464de1c45so909564d50.2 for ; Thu, 11 Dec 2025 21:15:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1765516550; x=1766121350; darn=vger.kernel.org; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=KPFmcLhqBnBTcaIEv2PJZuGjTwqiV4AuTcMDvkQwEyw=; b=AR679X4Lg0a8uIGpeXSwKZj97qZAC18ZyB2XPMSqfS3ZdK5z+5Ow0aKKb0bj1o44Iu LlFbbeQnyRoWpBGqeJ7BXv8meO4fzg6LvVNtXphbArTHMAHqTb2z0O37Tbt+QmbnMMCJ qtY+5FDbRwA1TFZdlKO2Keg7BYSc3oB0dk/38vKdmYqifUwEMdzvFxCRqQw3fGBMVoub ef8NVJ+ighXJYIRdRAO2hi4xo3n4wEFb9f7SO+eTbrgyp33sD9qbkPdYXlMOCWOZOIvE vFSaU/9CJBfheGkJ+/VNO310EKWPYEJSzKGGYwOm/jFSHfJ/F5gXQHzs/W77N5TcJ0k/ PMtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765516550; x=1766121350; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=KPFmcLhqBnBTcaIEv2PJZuGjTwqiV4AuTcMDvkQwEyw=; b=iLYTTvBXcOqv2/xrDFoLN6z+PFqd99xBXNw2mqUSWK/naWIOqtbb/XtELQ272MJR6U EYFk7ch/4EsUNdBqEA4O8151H3HH+oJgOj+arxaEOXOvWf6zWnbDjBe3+pzOLegHnNTy N+LzoO93WTNwTHN0Iu93IXl8Oo3yNVZu6B3ChCgcVrJzS5q5cuQLoK86f//FSXd8d7GS 6RX8XaMut6E5IGcbsa28MqQnh1winpoYudAjGUtDDICElV8sl2qU2QxN4HYt3bOlOhGI V1CczP5u6atRF1M85VJsZSmVZAyLrNrltHJTEf28n+OW35MSkFFxuRbZmay1pwQ/sv7R 3GAg== X-Forwarded-Encrypted: i=1; AJvYcCUELF/8HsSnY3QPfNRkCyZdS46sRkT0OvD5TQ+L+P3lTY+5vbQoe3VY3mumLrT/VkwBaFW61HAVrRjslzS6@vger.kernel.org X-Gm-Message-State: AOJu0Yy39N2fy6lw1MY2SSKm0a096irCAI5+7ZoVQ2X4NcfJZ7aS+R5m ZlYtUWzr5IkVKeuwwnruV+Mbh/6yBMC5zXdj8dn/d1icjm/29/iYIX3KONIerXdKig== X-Gm-Gg: AY/fxX7ukBIBkC0xE1LY56Mwj1NLUA78sRtitNnk3I3OLUieCAGmLOX+VAviIWtpJMu pgMDoQxREr+V1yQ/aGXJS3Rb33mUmRn5miFnCJo89CTCpbQg2A4F+0g2rI/igIa7rwXdyGz7jPp 9rc51KuZT5yl0Hu7forPlRhjJnjOwG0QkvIZyE0ydVXSMwwqm/Ww5Mi0YcE/8CnHAWOVyGz7FSC QqzNk7RaISiEr098orbZ089M89UVrpQ0dZJ8KISCvemyykghKQJANMVZcOqF81Q3pB5lcIX5WRj TQmv6+j05m2u2PL7QgRC1u/kmkiPUWLcT6QehvmFXjMHy/nW+xxjN8llNHJeNS2aJYiXIZ2sAzF xITJBWnVCbJ0khtobyVp62navLquRz8SMkmZCh5aV0/5CoFqxZQclW9q2MymlFTPkyT4U7q3duv IoVxwl04f25oieFhtMaiPuSU84QJktqJmBhIGelnPa4H2YFsybCZF9DSSBY+U8ynhXGbTW8LzJq tzG1wtRzw== X-Google-Smtp-Source: AGHT+IGj4VXQERBjFBx4z8QJxqfKFrAr0raivKj93bfeYMOpD2/ljOQYzi5YzTwvUjTi4XXcYyBnYQ== X-Received: by 2002:a53:cc0f:0:b0:640:db91:33c4 with SMTP id 956f58d0204a3-645555d245cmr503152d50.18.1765516550148; Thu, 11 Dec 2025 21:15:50 -0800 (PST) Received: from darker.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id 00721157ae682-78e6a2161bcsm1378637b3.25.2025.12.11.21.15.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Dec 2025 21:15:49 -0800 (PST) Date: Thu, 11 Dec 2025 21:15:37 -0800 (PST) From: Hugh Dickins To: Al Viro cc: Hugh Dickins , Christian Brauner , Andrew Morton , Baolin Wang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: 6.19 tmpfs __d_lookup() lockup In-Reply-To: <20251212050225.GD1712166@ZenIV> Message-ID: <7f288332-5514-e2ed-69e2-50c5e0304d92@google.com> References: <47e9d03c-7a50-2c7d-247d-36f95a5329ed@google.com> <20251212050225.GD1712166@ZenIV> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Fri, 12 Dec 2025, Al Viro wrote: > On Thu, Dec 11, 2025 at 07:56:38PM -0800, Hugh Dickins wrote: > > > Of course, 2313598222f9 ("convert ramfs and tmpfs") (of Feb 26 2024!) > > comes out as the first failing commit, no surprise there. > > > > I did try inserting a BUG_ON(node == node->next) on line 2438 of > > fs/dcache.c, just after __d_lookup's hlist_bl_for_each_entry_rcu(), > > and that BUG was immediately hit (but, for all I know, perhaps that's > > an unreliable asserition, perhaps it's acceptable for a race to result > > in a momentary node == node->next there). > > Hmm... Could you check if we are somehow hitting d_in_lookup(dentry) > in d_make_persistent()? Am I being stupid and misunderstanding you? I haven't tried running with any printks, it seems obvious from the source that d_make_persistent() always calls __d_instantiate(), which has a WARN_ON(d_in_lookup(dentry)) at the start. But I didn't see that warning fire on any occasion. Hugh