From nobody Thu Oct 2 23:48:29 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) (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 B3DE3334722; Tue, 9 Sep 2025 12:42:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757421765; cv=none; b=DILGcTf6t6o49bqa6N4KYiUqhD8TqQNmcgW6bbD/Y1oT/3EyoHTVvSfHYCXYkt+0EYF2UZVxyvxhUXNmj0usY0dSj4mXX7SCVXecGl8Nk9gWlohyLHjD1xn1rGQId7O7ljrYw0QMlBl+rXmvFj66JPmV+ousJ9zdHK/jIMHUC1U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757421765; c=relaxed/simple; bh=HXMhf8VGncxYHCwDK/v+GA73/bpOnN36hTkT2QbX1Oc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VvD+BaVkCVPa07ImoT4Ez1vpnWP4h9hZnRK2ZqGoKcFcCQYUnPcw14Mv1/W1JghQJRI/p1dxVxhrgQuHuxjpCDxP7Hn7Cn26I3NIDY/Abwz9uL0kq2kFHHyCah7UbM8WWY3QSZPAxYnA1n6s0V/WtfSwsQ+zEcsMnoS5dnZ8RT8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Fmj69ral; arc=none smtp.client-ip=192.198.163.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Fmj69ral" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1757421764; x=1788957764; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=HXMhf8VGncxYHCwDK/v+GA73/bpOnN36hTkT2QbX1Oc=; b=Fmj69ralNgucutJUTPnCXvNSzXfy8PqSdDirEw66g08yxGnNyq5bzX1w dQlEuHZvV8zP2d8DYXgm9lQBAlZjUXxI3/e97JxeZsskt+BhqLEXs1VNR 86ykPWH3CMVkhqXiRjRyYLF7KBbA7FmdYNa9cKzTUeijk7zQpziMD4RQl xnRqGtAd7v8l9X6WaY/gmGWy/2hj8IPAYtf4pGGkbV5NIEReDbI/ugF/2 wCqXbibheLuseJkI5+68j2AZ7dcBnYevEhL2tHSllyOLjkY0bq2SKj9Ve iEtIEy3HRSxELz/N1kNpnnaBHgchqyrIqsvHE0AlKTKsKlUnxIlJnxObj g==; X-CSE-ConnectionGUID: HZ2e26RfTp+KtM5x/i4yxQ== X-CSE-MsgGUID: q0glqhm0QkuiIK3SEpYe3Q== X-IronPort-AV: E=McAfee;i="6800,10657,11547"; a="70399556" X-IronPort-AV: E=Sophos;i="6.18,251,1751266800"; d="scan'208";a="70399556" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Sep 2025 05:42:43 -0700 X-CSE-ConnectionGUID: c+vPT1/MSpm46JdSgeOfJw== X-CSE-MsgGUID: 0n1u8bFiRYW6T/2X/rpE2w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,251,1751266800"; d="scan'208";a="172667451" Received: from abityuts-desk.ger.corp.intel.com (HELO localhost.localdomain) ([10.245.244.84]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Sep 2025 05:42:39 -0700 From: Adrian Hunter To: Peter Zijlstra Cc: Ingo Molnar , Alexander Shishkin , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Mark Rutland , Ian Rogers , Kan Liang , Mathieu Poirier , Miklos Szeredi , Alexander Viro , Christian Brauner , Amir Goldstein , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH 2/3] perf/core: Fix MMAP event path names with backing files Date: Tue, 9 Sep 2025 15:42:21 +0300 Message-ID: <20250909124222.222945-3-adrian.hunter@intel.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250909124222.222945-1-adrian.hunter@intel.com> References: <20250909124222.222945-1-adrian.hunter@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Some file systems like FUSE-based ones or overlayfs may record the backing file in struct vm_area_struct vm_file, instead of the user file that the user mmapped. Since commit def3ae83da02f ("fs: store real path instead of fake path in backing file f_path"), file_path() no longer returns the user file path when applied to a backing file. There is an existing helper file_user_path() for that situation. Use file_user_path() instead of file_path() to get the path for MMAP and MMAP2 events. Example: Setup: # cd /root # mkdir test ; cd test ; mkdir lower upper work merged # cp `which cat` lower # mount -t overlay overlay -olowerdir=3Dlower,upperdir=3Dupper,workdir= =3Dwork merged # perf record -e intel_pt//u -- /root/test/merged/cat /proc/self/maps ... 55b0ba399000-55b0ba434000 r-xp 00018000 00:1a 3419 = /root/test/merged/cat ... [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.060 MB perf.data ] # Before: File name is wrong (/cat), so decoding fails: # perf script --no-itrace --show-mmap-events cat 367 [016] 100.491492: PERF_RECORD_MMAP2 367/367: [0x= 55b0ba399000(0x9b000) @ 0x18000 00:02 3419 489959280]: r-xp /cat ... # perf script --itrace=3De | wc -l Warning: 19 instruction trace errors 19 # After: File name is correct (/root/test/merged/cat), so decoding is ok: # perf script --no-itrace --show-mmap-events cat 364 [016] 72.153006: PERF_RECORD_MMAP2 364/364:= [0x55ce4003d000(0x9b000) @ 0x18000 00:02 3419 3132534314]: r-xp /root/test= /merged/cat # perf script --itrace=3De # perf script --itrace=3De | wc -l 0 # Fixes: def3ae83da02f ("fs: store real path instead of fake path in backing = file f_path") Cc: stable@vger.kernel.org Signed-off-by: Adrian Hunter Acked-by: Amir Goldstein --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 184f3dc7b03b..e203b8d90fd2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9416,7 +9416,7 @@ static void perf_event_mmap_event(struct perf_mmap_ev= ent *mmap_event) * need to add enough zero bytes after the string to handle * the 64bit alignment we do later. */ - name =3D file_path(file, buf, PATH_MAX - sizeof(u64)); + name =3D d_path(file_user_path(file), buf, PATH_MAX - sizeof(u64)); if (IS_ERR(name)) { name =3D "//toolong"; goto cpy_name; --=20 2.48.1