From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) by lore.proxmox.com (Postfix) with ESMTPS id 44EB31FF13B for ; Wed, 22 Apr 2026 09:34:08 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 25ED1D20C; Wed, 22 Apr 2026 09:34:08 +0200 (CEST) From: Christian Ebner To: pbs-devel@lists.proxmox.com Subject: [PATCH proxmox] shared-memory: flush contents of newly created mmap file Date: Wed, 22 Apr 2026 09:33:51 +0200 Message-ID: <20260422073351.181581-1-c.ebner@proxmox.com> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1776843157455 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.070 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment KAM_SHORT 0.001 Use of a URL Shortener for very short URL SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [man7.org,lib.rs,proxmox.com] Message-ID-Hash: PYUTYJJ43AGHVY63242ZSTLV3OJTAZJD X-Message-ID-Hash: PYUTYJJ43AGHVY63242ZSTLV3OJTAZJD X-MailFrom: c.ebner@proxmox.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.10 Precedence: list List-Id: Proxmox Backup Server development discussion List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: The man page for mmap [0] states, that mappings create with `MAP_SHARED` are not carried to the underlying file directly. To avoid possible races between creating and initializing a new mmapped file and opening while checking the header of this file, msync the contents after init but before persisting the shared memory backed file. [0] https://man7.org/linux/man-pages/man2/mmap.2.html Fixes: https://forum.proxmox.com/threads/182948/ Signed-off-by: Christian Ebner --- proxmox-shared-memory/src/lib.rs | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/proxmox-shared-memory/src/lib.rs b/proxmox-shared-memory/src/lib.rs index 495812ef..4838ab42 100644 --- a/proxmox-shared-memory/src/lib.rs +++ b/proxmox-shared-memory/src/lib.rs @@ -190,6 +190,10 @@ impl SharedMemory { let mmap = mmap_file(&mut file, true)?; + if skip_tmpfs_check { + mmap.msync(MsFlags::MS_SYNC)?; + } + let res = { let path = CString::new(path.as_os_str().as_bytes())?; Errno::result(unsafe { -- 2.47.3