{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-98818", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-98818", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-10-18T15:49:10.258Z", "updatedAt": "2026-10-19T09:26:11.267Z", "importedAt": "2026-10-24T01:58:41.756Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "mm/slab: do not wake up kswapd in __kfree_rcu_sheaf()", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/slab: do not wake up kswapd in __kfree_rcu_sheaf()\n\nSince kfree_rcu() can be called under pi_lock (a raw spinlock in the\nscheduler), kfree_rcu() itself should never allocate memory with\n__GFP_KSWAPD_RECLAIM as waking up kswapd ends up acquiring pi_lock,\nwhich leads to a deadlock.\n\nReproducing the issue even intentionally was not straightforward.\nThe set_cpus_allowed_force() path that is called under pi_lock is\nexercised very rarely, and competing tasks that allocate memory will\nmost likely wake kswapd up.\n\nTherefore the existence of the deadlock was verified with a modified\nkernel that has a lockdep map for waking up kswapd:\n\n ======================================================\n WARNING: possible circular locking dependency detected\n 7.2.0-rc1-slab-for-next+ #10 Not tainted\n ------------------------------------------------------\n git/6660 is trying to acquire lock:\n ffff8e524533c550 (&p->pi_lock){-.-.}-{2:2}, at: _raw_spin_lock_irqsave+0x12/0x20\n\n but task is already holding lock:\n ffff8e57bffff1a0 (&pgdat->kswapd_wait){....}-{3:3}, at: _raw_spin_lock_irqsave+0x12/0x20\n\n which lock already depends on the new lock.\n\n the existing dependency chain (in reverse order) is:\n\n -> #2 (&pgdat->kswapd_wait){....}-{3:3}:\n __lock_acquire+0x5a4/0xc50\n lock_acquire.part.0+0xb7/0x240\n lock_acquire+0x70/0x170\n __raw_spin_lock_irqsave+0x44/0x80\n _raw_spin_lock_irqsave+0x12/0x20\n __wake_up_common_lock+0x31/0xa0\n __wake_up+0x20/0x40\n kswapd_wakeup_wake+0x7e/0x110\n wakeup_kswapd+0x295/0x320\n wake_all_kswapds+0xac/0x1a0\n __alloc_pages_slowpath.constprop.0+0x282/0xf80\n __alloc_frozen_pages_noprof+0x32a/0x360\n alloc_slab_page+0x2e/0x160\n allocate_slab+0x82/0x420\n new_slab+0x52/0xb0\n refill_objects+0x13d/0x190\n refill_sheaf+0x5d/0xd0\n __pcs_replace_empty_main+0x230/0xb10\n [...]\n\n -> #1 (kswapd_wakeup){-.-.}-{0:0}:\n __lock_acquire+0x5a4/0xc50\n lock_sync.part.0+0x75/0x100\n lock_sync+0x36/0x70\n might_wakeup_kswapd+0x61/0xa0\n __kfree_rcu_sheaf+0x33/0xd90\n kvfree_call_rcu+0x1d4/0x3b0\n set_cpus_allowed_force+0x163/0x220\n cpuset_cpus_allowed_fallback+0x18b/0x240\n select_fallback_rq+0x1e6/0x250\n\t [...]\n\n -> #0 (&p->pi_lock){-.-.}-{2:2}:\n check_prev_add+0xe6/0xe00\n validate_chain+0x51e/0x6e0\n __lock_acquire+0x5a4/0xc50\n lock_acquire.part.0+0xb7/0x240\n lock_acquire+0x70/0x170\n __raw_spin_lock_irqsave+0x44/0x80\n _raw_spin_lock_irqsave+0x12/0x20\n try_to_wake_up+0x77/0xa90\n default_wake_function+0x27/0x60\n autoremove_wake_function+0x23/0xb0\n __wake_up_common+0xb8/0x170\n __wake_up_common_lock+0x51/0xa0\n __wake_up+0x20/0x40\n kswapd_wakeup_wake+0x7e/0x110\n wakeup_kswapd+0x295/0x320\n wake_all_kswapds+0xac/0x1a0\n __alloc_pages_slowpath.constprop.0+0x282/0xf80\n __alloc_frozen_pages_noprof+0x32a/0x360\n alloc_slab_page+0x2e/0x160\n allocate_slab+0x82/0x420\n new_slab+0x52/0xb0\n refill_objects+0x13d/0x190\n refill_sheaf+0x5d/0xd0\n __pcs_replace_empty_main+0x230/0xb10\n [...]\n\n other info that might help us debug this:\n\n Chain exists of:\n &p->pi_lock --> kswapd_wakeup --> &pgdat->kswapd_wait\n\n Possible unsafe locking scenario:\n\n CPU0 CPU1\n ---- ----\n lock(&pgdat->kswapd_wait);\n lock(kswapd_wakeup);\n lock(&pgdat->kswapd_wait);\n lock(&p->pi_lock);\n\n *** DEADLOCK ***\n\n 3 locks held by git/6660:\n #0: ffff8e519f0e9e20 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: lookup_slow+0x2d/0x60\n #1: ffffffff8a31c460 (kswapd_wakeup){-.-.}-\n---truncated---", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "ec66e0d599520ab414db745544e25d80d0ac5054", "status": "affected", "versionType": "git", "lessThan": "46545c86b54ffb969b6e3662942b4a6191619eaa" }, { "version": "ec66e0d599520ab414db745544e25d80d0ac5054", "status": "affected", "versionType": "git", "lessThan": "af2fb3ee6679b517e2fdbd3ba16ec276a8b74312" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.18", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.18" }, { "version": "7.2.10", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }