From nobody Wed Sep 30 09:58:33 2026 Received: from mail-pl1-f175.google.com (mail-pl1-f175.google.com [209.85.214.175]) (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 04AEB416842 for ; Wed, 12 Aug 2026 09:54:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.175 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786528484; cv=none; b=T2lk/DeGHA3jDuXuVB6ryNoX/hUZniRZiLBfGFAJtDKm/RqjRHG61QKeZq7wD3/U1j9Fe2QchFFDniqoJBS/9zjwvBVdMogkBxSQI/dHMD2n74/Y5yG2elDFnYf0yGbMWFWvq+OxzOotYu5hmu8LwSNBx4PbaVfo4+P9UrB0Bew= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786528484; c=relaxed/simple; bh=IfqoZFGbmTJ7IoZMb7y+zk4ULZ3VhowOkmWTKnvw7/o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=p+oIcTKzHqm/IV8iJ+EDHqDK7URGbFZkp8Bp9n2+2puMej2war50SPs3WYCWRFAdSviTsrltE2JdV7Wgggzwe1Kk9Nea3pXTNvmNXCFRPdJbRvJq4MKISUdFxxZnV9Sw4liWrKitEcQbVUoICqELJfmvS3xqB1AF58ySFrgjxPY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=a8fjlw4o; arc=none smtp.client-ip=209.85.214.175 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="a8fjlw4o" Received: by mail-pl1-f175.google.com with SMTP id d9443c01a7336-2cca0c5799eso10310025ad.0 for ; Wed, 12 Aug 2026 02:54:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1786528481; x=1787133281; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=td3fCdxPcYCOcpgILhIJ1zG9gCZ53qHXXoPGzD17mEE=; b=a8fjlw4oahV7xDzCSIqxksSxdhyHCCM7ivhNmBA4X6v1AzznZaBdcv+e5GtXCH0GdM PsKR/yUAR0hipzQqcm8fmEZc1tIX9pFE6klPo/lfTJ0HMJ9qn5kDdTXweLNalBlHgfOw gdP0zKKBc2RM7srVV3OxM2//6VGLz7pS+8jRc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786528481; x=1787133281; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=td3fCdxPcYCOcpgILhIJ1zG9gCZ53qHXXoPGzD17mEE=; b=M1tVb++iLUZcTrzigjZq/vhM5puyt84uqx9u3YDfKmHWoAfq4wGVrUbsZNgK9029H7 lKfXCypEZ1INzqCBNLWon9IS9HeazmIY+em2LrrPDmSGxEWZkpgNfSgGkGWePb9ene4e ejeGu57yv/Sc4LmTVcEENQHZTiSe1kmxPXUKjiOActahUJ4I2UndGGJakVClMfsp2mlY KjijI7AGVi5bb2M6fD65Qc4qYRtxAKUdOK9gVE01Y6oi9tayqhVh0q/hnm6ZrENen/K/ D2zQY1aRM8cGRhWoqaKZdPckMPDQ70a9mVGcxQovJAqKFuulogcZWaOWoK0yi0VuUwt/ zYaA== X-Forwarded-Encrypted: i=1; AHgh+RqTJJzQX4+9ozeyOxWAT/IjncW0jNAscJMKyGAIycM0JrSCqRseH9TMYEN8Z0im00AVVEJ0D7Hh9bfvRAg=@vger.kernel.org X-Gm-Message-State: AOJu0YzyWIGLhN8swoWnhVj9OUjRZHtLfWQrhz/R280dCpvzJyn478vM P+j9YFlBRbmQh4J20blHvFf0pTnf6X4QHVvuw2sddusdXJQt1KM0r7skCtLbHIJIxg== X-Gm-Gg: AR+sD10wNPs+G0npiNAPLxLNSrHeHVGEdKsGgaXiKZGamPIBrOD6r3JaZzvoo02iKq2 nKPg5JRcLTGhHlUx2NZ+W+6FAOJmjrLZGIs3uGeQL0qcH3+G8KzXI1MeMlibQUpPrQ/1R/ql9w7 /vVRulbIPTqX0fqIL6h1/wjQ5NGqBQ+Tic8U07HYkdDQcsIsUjUocUayTCCXhXsYtYIs9wOpY0E ZdvfiVFdT2Jq4gywSw3mUprGEyRv/H6f6bpG/q1bTxjrObQK9yiHXt1prDwA9zIh/yWq1llogBU ytg4Nh4ky8zwVbY4qbUaX1srFJrRbT3aEjlYW5kvvmeuVOUO5MF9QZsEUgkw0pLpIBx1cFrW5wp AYtBG9nq1hyyXBzL8eqD81B2kPJGZei2Uj/YSZvAW9xy5jyrTv0SHQozL7QFPXuRYo+tHxOgOdF xe5VQ9U4bmmrOgeRd5ar9JCrpj2skFzngSccQwpDhoRNqOhkN3PEGOWF1IKgnauFPj9YPXAX0n4 eKhmoskwU9k4LP6LIo6ADVG2boy71hJsfKKRhtqgbwRq/HQ5kE= X-Received: by 2002:a17:903:2305:b0:2c9:b8b7:5d1c with SMTP id d9443c01a7336-2d34569b9demr33087725ad.16.1786528481279; Wed, 12 Aug 2026 02:54:41 -0700 (PDT) Received: from tigeriii.tok.corp.google.com ([2a00:79e0:2031:6:6d46:aa38:60df:e1e]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d35220c8edsm3953695ad.66.2026.08.12.02.54.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Aug 2026 02:54:40 -0700 (PDT) From: Sergey Senozhatsky To: Miklos Szeredi Cc: fuse-devel@lists.linux.dev, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: [RFC PATCH] fuse: permit freezing while waiting for request answer Date: Wed, 12 Aug 2026 18:54:20 +0900 Message-ID: <20260812095431.1216919-1-senozhatsky@chromium.org> X-Mailer: git-send-email 2.55.0.679.g6767b8d81c-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Suspend freezes tasks in random order and doesn't take into consideration producer-consumer dependency that may exist between tasks. One example where this can cause issues is: fuse server getting frozen ahead of clients, which then get stuck waiting for req answers that never come (the server is already frozen): PM: suspend entry (s2idle) Filesystems sync: 0.018 seconds Freezing user space processes Freezing user space processes failed after 20.001 seconds (1 tasks refusin= g to freeze, wq_busy=3D0): task:ThreadPoolForeg state:D stack:0 pid:7873 tgid:7854 ppid:7827 = flags:0x00004006 Call Trace: __schedule+0x554/0x1320 ? vprintk_emit+0x2a8/0x320 schedule+0x5e/0xd0 __fuse_simple_request+0x4c8/0x6d0 fuse_do_getattr+0x1e9/0x320 fuse_update_get_attr+0x362/0x6a0 fuse_file_read_iter+0x13a/0x1b0 vfs_read+0x29f/0x2f0 ksys_read+0x75/0xf0 do_syscall_64+0x70/0xf0 Make all wait-event calls in request_wait_answer() freezer-friendly. This uses TASK_FREEZABLE_UNSAFE because often time we freeze holding locks (in the upper layers), which triggers debug_locks warning. Signed-off-by: Sergey Senozhatsky --- fs/fuse/dev.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 27dafda2a841..9e98ece4143f 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -703,8 +703,10 @@ static void request_wait_answer(struct fuse_req *req) =20 if (!fch->no_interrupt) { /* Any signal may interrupt this */ - err =3D wait_event_interruptible(req->waitq, - test_bit(FR_FINISHED, &req->flags)); + err =3D wait_event_state(req->waitq, + test_bit(FR_FINISHED, &req->flags), + TASK_INTERRUPTIBLE | + TASK_FREEZABLE_UNSAFE); if (!err) return; =20 @@ -719,8 +721,9 @@ static void request_wait_answer(struct fuse_req *req) bool removed; =20 /* Only fatal signals may interrupt this */ - err =3D wait_event_killable(req->waitq, - test_bit(FR_FINISHED, &req->flags)); + err =3D wait_event_state(req->waitq, + test_bit(FR_FINISHED, &req->flags), + TASK_KILLABLE | TASK_FREEZABLE_UNSAFE); if (!err) return; =20 @@ -741,7 +744,8 @@ static void request_wait_answer(struct fuse_req *req) * Either request is already in userspace, or it was forced. * Wait it out. */ - wait_event(req->waitq, test_bit(FR_FINISHED, &req->flags)); + wait_event_state(req->waitq, test_bit(FR_FINISHED, &req->flags), + TASK_UNINTERRUPTIBLE | TASK_FREEZABLE_UNSAFE); } =20 static void __fuse_request_send(struct fuse_req *req) --=20 2.55.0.679.g6767b8d81c-goog