{"id":"CVE-2025-38063","title":"dm: fix unconditional IO throttle caused by REQ_PREFLUSH","summary":"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 …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 95d08924335f3b6f4ea0b92ebfe4fe0731c502d9","Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 52aa28f7b1708d76e315d78b5ed397932a1a97c3","Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < b55a97d1bd4083729a60d19beffe85d4c96680de","Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 2858cda9a8d95e6deee7e3b0a26adde696a9a4f5","Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 88f7f56d16f568f19e1a695af34a7f4a6ce537a6","Linux 4.10"],"published":"2025-06-18","updated":"2026-10-15","sourceUpdated":"2026-10-15T01:06:24.829Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-38063","references":[{"url":"https://git.kernel.org/stable/c/95d08924335f3b6f4ea0b92ebfe4fe0731c502d9"},{"url":"https://git.kernel.org/stable/c/52aa28f7b1708d76e315d78b5ed397932a1a97c3"},{"url":"https://git.kernel.org/stable/c/b55a97d1bd4083729a60d19beffe85d4c96680de"},{"url":"https://git.kernel.org/stable/c/2858cda9a8d95e6deee7e3b0a26adde696a9a4f5"},{"url":"https://git.kernel.org/stable/c/88f7f56d16f568f19e1a695af34a7f4a6ce537a6"}],"tags":["cve.org"],"epss":0.00182,"epssPercentile":0.07718,"ingestedAt":"2026-10-15T05:52:46.098Z","slug":"CVE-2025-38063","body":"## Overview\n\nIn 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> 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().\n\n## Affected\n\n- `Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 95d08924335f3b6f4ea0b92ebfe4fe0731c502d9`\n- `Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 52aa28f7b1708d76e315d78b5ed397932a1a97c3`\n- `Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < b55a97d1bd4083729a60d19beffe85d4c96680de`\n- `Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 2858cda9a8d95e6deee7e3b0a26adde696a9a4f5`\n- `Linux >= e34cbd307477ae07c5d8a8d0bd15e65a9ddaba5c < 88f7f56d16f568f19e1a695af34a7f4a6ce537a6`\n- `Linux 4.10`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}