{"id":"CVE-2025-38063","summary":"dm: fix unconditional IO throttle caused by REQ_PREFLUSH","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm: fix unconditional IO throttle caused by REQ_PREFLUSH\n\nWhen a bio with REQ_PREFLUSH is submitted to dm, __send_empty_flush()\ngenerates a flush_bio with REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC,\nwhich causes the flush_bio to be throttled by wbt_wait().\n\nAn example from v5.4, similar problem also exists in upstream:\n\n    crash\u003e bt 2091206\n    PID: 2091206  TASK: ffff2050df92a300  CPU: 109  COMMAND: \"kworker/u260:0\"\n     #0 [ffff800084a2f7f0] __switch_to at ffff80004008aeb8\n     #1 [ffff800084a2f820] __schedule at ffff800040bfa0c4\n     #2 [ffff800084a2f880] schedule at ffff800040bfa4b4\n     #3 [ffff800084a2f8a0] io_schedule at ffff800040bfa9c4\n     #4 [ffff800084a2f8c0] rq_qos_wait at ffff8000405925bc\n     #5 [ffff800084a2f940] wbt_wait at ffff8000405bb3a0\n     #6 [ffff800084a2f9a0] __rq_qos_throttle at ffff800040592254\n     #7 [ffff800084a2f9c0] blk_mq_make_request at ffff80004057cf38\n     #8 [ffff800084a2fa60] generic_make_request at ffff800040570138\n     #9 [ffff800084a2fae0] submit_bio at ffff8000405703b4\n    #10 [ffff800084a2fb50] xlog_write_iclog at ffff800001280834 [xfs]\n    #11 [ffff800084a2fbb0] xlog_sync at ffff800001280c3c [xfs]\n    #12 [ffff800084a2fbf0] xlog_state_release_iclog at ffff800001280df4 [xfs]\n    #13 [ffff800084a2fc10] xlog_write at ffff80000128203c [xfs]\n    #14 [ffff800084a2fcd0] xlog_cil_push at ffff8000012846dc [xfs]\n    #15 [ffff800084a2fda0] xlog_cil_push_work at ffff800001284a2c [xfs]\n    #16 [ffff800084a2fdb0] process_one_work at ffff800040111d08\n    #17 [ffff800084a2fe00] worker_thread at ffff8000401121cc\n    #18 [ffff800084a2fe70] kthread at ffff800040118de4\n\nAfter commit 2def2845cc33 (\"xfs: don't allow log IO to be throttled\"),\nthe metadata submitted by xlog_write_iclog() should not be throttled.\nBut due to the existence of the dm layer, throttling flush_bio indirectly\ncauses the metadata bio to be throttled.\n\nFix this by conditionally adding REQ_IDLE to flush_bio.bi_opf, which makes\nwbt_should_throttle() return false to avoid wbt_wait().","modified":"2026-04-02T12:47:46.729015Z","published":"2025-06-18T09:33:41.977Z","related":["SUSE-SU-2025:02853-1","SUSE-SU-2025:02923-1","SUSE-SU-2025:02969-1","SUSE-SU-2025:02996-1","SUSE-SU-2025:02997-1","SUSE-SU-2025:03011-1","SUSE-SU-2025:03023-1","SUSE-SU-2025:20577-1","SUSE-SU-2025:20586-1","SUSE-SU-2025:20601-1","SUSE-SU-2025:20602-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38063.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2858cda9a8d95e6deee7e3b0a26adde696a9a4f5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/52aa28f7b1708d76e315d78b5ed397932a1a97c3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/88f7f56d16f568f19e1a695af34a7f4a6ce537a6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/95d08924335f3b6f4ea0b92ebfe4fe0731c502d9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b55a97d1bd4083729a60d19beffe85d4c96680de"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38063.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38063"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c"},{"fixed":"95d08924335f3b6f4ea0b92ebfe4fe0731c502d9"},{"fixed":"52aa28f7b1708d76e315d78b5ed397932a1a97c3"},{"fixed":"b55a97d1bd4083729a60d19beffe85d4c96680de"},{"fixed":"2858cda9a8d95e6deee7e3b0a26adde696a9a4f5"},{"fixed":"88f7f56d16f568f19e1a695af34a7f4a6ce537a6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38063.json"}}],"schema_version":"1.7.5"}