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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1777622251; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=kyAk8NA2J8YQgw/gGqBaVOWUHWOA6WWmvSiQgKxkb6M=; b=lPQlJNofp7eLTUX3eNkcXz9TPqr+ahTmftjh5QsREqS0S2al9UrBTHMVb/Z0shGSMIRX40 4KGc2Fz54IwH7pt0+UvqdG6n31XxJkVdF27ly2VC0Em2A1d8opzTh/GXu+mT6pOP0EHFat xC7Gxe3IU10Uf5VxmAcoqg21T9MdDQg= From: Ye Liu To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes Cc: Ye Liu , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/khugepaged: clear MMF_VM_HUGEPAGE on mm_slot_alloc() failure Date: Fri, 1 May 2026 15:57:07 +0800 Message-ID: <20260501075708.327217-1-ye.liu@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 19A74120002 X-Stat-Signature: j1g1i8r4zkscwh8sazat1d3orb5qgnho X-Rspam-User: X-HE-Tag: 1777622292-410768 X-HE-Meta: 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 jW1FpACr fGnKs2/wYkH9srQq5gVIpcFLuv/8A/tsIZyencOT8Hmp+rRgF3Yrv8p9atUCQJsSp4vfn41M6ld63vObOOsu6OTxU/naXt5Eit3njcpZ7pByUmahZAgWz9lKlKbj911idAYe2P37eTAuYnNs8PyRn9ZvUWpyq4fqPVDSpcvxth02Wg/cos61d1vsHYtq/qU0HODX3TcnIsNS5ItNE9RsMyIW4wm7kVouARcv5COYnPLM5+gzR+ItmutDEiw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ye Liu __khugepaged_enter() sets MMF_VM_HUGEPAGE before allocating the corresponding mm_slot. If mm_slot_alloc() fails, the function returns with the flag set but without inserting the mm into the khugepaged tracking structures. This leaves the mm in an inconsistent state: it is marked as registered (MMF_VM_HUGEPAGE set), but will never be scanned by khugepaged. Future attempts to register the mm are skipped since khugepaged_enter_vma() checks the flag and returns early. Fix this by clearing MMF_VM_HUGEPAGE when mm_slot_alloc() fails, restoring the ability to retry registration later. Signed-off-by: Ye Liu --- mm/khugepaged.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 7d48d4fbd5f3..60ab7c1b61dd 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -559,8 +559,10 @@ void __khugepaged_enter(struct mm_struct *mm) return; slot = mm_slot_alloc(mm_slot_cache); - if (!slot) + if (!slot) { + mm_flags_clear(MMF_VM_HUGEPAGE, mm); return; + } spin_lock(&khugepaged_mm_lock); mm_slot_insert(mm_slots_hash, mm, slot); -- 2.43.0