From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta0.migadu.com (out-183.mta0.migadu.com [91.218.175.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 01E2B1A683F for ; Wed, 6 May 2026 01:21:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778030506; cv=none; b=YKoVp84jwscBRSPQ6OZ20GWUnsCwkb3a38bpVrNOStVIPVZgOZU58DAXJuUvCUBRe0KQ1hdZO4f3n8GIIwDR8csCWA/J9gxEflBPkKMJjw7DPXwTMb7Pi93MDyV7BLNhPew1z6AC78MhIbsDmp9m0YMdEQ7hc3fDPLJiLth4Bxs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778030506; c=relaxed/simple; bh=9jjdDIMQApP/Tt4QzNT5JHYas+Mn1USHasmfEl7R8Dw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=F8bPc3uEpuDKDNTPNIzJVDU2EzjvhzGNAw0L8YB3dHaYyxVAN478ub7Lp2kptsPmscguyiRVaFCI/IzNzWTS+GrVeJ5I4ZRb+pGZ8uIWnWEZwOfGcR+pTbWAM1C9IgSpzkwOoq2CFwh/JQqW3w86d0pZc/8PtrYFiKiafaVxNLM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nM0/9VYT; arc=none smtp.client-ip=91.218.175.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="nM0/9VYT" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1778030502; 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=jo8MCaaDwyNkPCffzoxVKxauIzsXTxzjbuGF97idt1g=; b=nM0/9VYTzZIhU0s9ulfmX322LYJrIrZGfM2kpijuCrp8ZhLOqOnV+43leQTduDtr0tZOlj 4V9I2PpSPd4LNSPORv6dX1Zicl5P59hig2ooY7dhHzJlJEIWUFqYEb+DUiGETm13w277D5 9Nhh+ZDnH+ovMUXx4/rhUuONPRHMQK0= From: Ye Liu To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Xin Hao Cc: Ye Liu , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] mm/khugepaged: clear MMF_VM_HUGEPAGE on mm_slot_alloc() failure Date: Wed, 6 May 2026 09:21:30 +0800 Message-ID: <20260506012130.9306-1-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 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. Fixes: 16618670276a ("mm: khugepaged: avoid pointless allocation for struct mm_slot") Signed-off-by: Ye Liu --- Changes since v1: - Add Fixes tag as suggested by Dev Jain and Lance Yang 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