From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-139.mta0.migadu.com [91.218.175.139]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8BDE5485CC3 for ; Fri, 2 Oct 2026 09:57:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.139 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790935027; cv=none; b=j+66YJofer1A/9ivqkRZFAWGatYfHo2sfpTUf9qgXCYlHZR5NKlgkPd23/LOFLYk0YgYFfux1hKYJlkA3mBvWDGdBIkcp96vr4517vtGfl4zEINgZemO+7rvkqkIWgrLGBTGhQcuxCXJ1uq3XrHzzTC2tTEEMp532Wd3WgnEgQY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790935027; c=relaxed/simple; bh=EsV4QmuE2zIVMKtO/SOhRrFUuEtNtiAe7xebMuMrx54=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BYzCb2Jfep/MZqi38Czwr3cc10LWGCr+/a8mIPNKThsRA5V+w2h9+d9eKaiOOJo0skR4u2QF01BiSUEbGLhTtiwSb/daDLKl9pPXljPMCOjkiZAE5wXpCPCtrWQVa/PIdUKLjSTvvpwIZjmdqb6p/rjM4ybsao9+6YOkWBCXQAc= 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=NeCRGXST; arc=none smtp.client-ip=91.218.175.139 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="NeCRGXST" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=EsV4QmuE2zIVMKtO/SOhRrFUuEtNtiAe7xebMuMrx54=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790935023; v=1; x=1791539823; b=NeCRGXSTGWfHGH9nTdqHnUHOoYToHUcfwajejK8iXk88Y2IhVI1ONvbD8VUmxLyOhGv8LhDZ WZz/2rZr+zCQsx6NahvNRERAo6khQdf77pwuvV8U4H/wrAX0gBooXejKZSb5NKfKqgS7vTtE6td pggSbfzxY5DEZuhRpW/yvIiM= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta12.migadu.com with ESMTPS id 3b859f7e4ff92309; Fri, 02 Oct 2026 09:57:03 +0000 X-Mizu-Trace-ID: 3b859f7e4ff92309 X-Migadu-Flow: FLOW_OUT From: Usama Arif To: Andrew Morton , david@kernel.org, chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com, linux-mm@kvack.org Cc: ying.huang@linux.alibaba.com, Baoquan He , willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, Nico Pache , Liam R. Howlett , ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, yosry@kernel.org, qi.zheng@linux.dev, luizcap@redhat.com, kernel-team@meta.com, Usama Arif Subject: [PATCH v8 18/30] mm/hmm: fault PMD swap entries on demand Date: Fri, 2 Oct 2026 02:52:32 -0700 Message-ID: <20261002095503.3585565-19-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261002095503.3585565-1-usama.arif@linux.dev> References: <20261002095503.3585565-1-usama.arif@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 hmm_vma_handle_absent_pmd() reports anything non-present that is not device-private as HMM_PFN_ERROR, so a swapped-out THP would look like a permanent failure rather than memory that needs paging in. Treat it like a PTE swap entry: record the fault when one was asked for, and otherwise report the range as non-resident with no flags, which is what hmm_vma_handle_pte() already does in snapshot mode. Signed-off-by: Usama Arif --- mm/hmm.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/hmm.c b/mm/hmm.c index 2f1e98c6b6440..95575ac378888 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -377,12 +377,21 @@ static int hmm_vma_handle_absent_pmd(struct mm_walk *walk, unsigned long start, required_fault = hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0); if (required_fault) { - if (softleaf_is_device_private(entry)) + if (softleaf_is_device_private(entry) || + softleaf_is_swap(entry)) return hmm_record_fault(addr, end, required_fault, walk); else return -EFAULT; } + /* + * A swapped-out THP is not resident. Report it as not-valid, + * matching what hmm_vma_handle_pte() does for a PTE swap entry when + * no fault was requested. + */ + if (softleaf_is_swap(entry)) + return hmm_pfns_fill(start, end, range, 0); + return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR); } #else -- 2.53.0-Meta