From nobody Fri Dec 19 04:01:23 2025 Received: from mail-qv1-f73.google.com (mail-qv1-f73.google.com [209.85.219.73]) (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 989EE217F48 for ; Wed, 26 Feb 2025 11:48:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740570504; cv=none; b=Wn7O3wGM/BujxIcJVYHix8z4UrLyb/O8ge68nmM9kICyZeSkgiqnF4hCiAPFAy5KCx5L86GIaymXfaTL0j4yR/iE/Sf7y3+e76sWl8oFO/A2xikjK8X9viMidCtyNzQpDIDU2mBOtMeMuC6pUXkhStFl7vuNXicZcmPSaIjCXCU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740570504; c=relaxed/simple; bh=NluUjPQ1lcXSGNSXHKkI9g2tFhg8Z04LMSmLkLhacJg=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=RoUQ21dEE9/VuJd45ccvSs1Ig40Zc+y0o0XQW+gcJhcflvoxPbR+cmGj09u6/AJ91CPAlf2c8fgOLvCiy07tjlz2kNhekd/7PTAcG3Lg8/su63wNy/PeH8+125BGssIfJCgHXCaeYurHtsKdOsZOuS+yR/j+BkTzRTJ6A/F+D2I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--bgeffon.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=bASzfkXc; arc=none smtp.client-ip=209.85.219.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--bgeffon.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="bASzfkXc" Received: by mail-qv1-f73.google.com with SMTP id 6a1803df08f44-6e867ab3537so54563536d6.0 for ; Wed, 26 Feb 2025 03:48:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740570501; x=1741175301; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=BW2sDZbGgcaHae82O3nWDg50TbU9r5oNGjDpd8Bq0yg=; b=bASzfkXcq6uDxnM3z9vcz2+aGdJN4NKqtup4GK2vxVtnyP+fgJVvuMkARXpYDOpwk8 IeNYqrWvf2DvIibDUErf/peL/5JR+W9MCyRE6yhQJnLeK3CKy/x59dcxKjwcuVNwsTyr N9cvyW5v6B+ZL/nO3JO7WfqoA6zYqOA1Gors36mb/aD1SK1A9ZGR5+ql1u6NOuOR4ycd 0WPia3G/HXFZw2qyfV7W9si6O0hS9uu9fsHffeiDPgwtmSVeEunBS+hDcRkFsGS75+uv 1rnj3tcxDuZzymkpiv/xNQAcVzWjlsvlzDZdmerOMPVKVdt5LUA7ZhjyA+89UjSISl1h vqsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740570501; x=1741175301; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=BW2sDZbGgcaHae82O3nWDg50TbU9r5oNGjDpd8Bq0yg=; b=vi6v+Tc+Pm9r4TAgPi1A0WpHLn2jRM9/ALgue+of2ce5lOjXPOCAqFFNmZ1pDxkSv+ FGpm1/RgDKuc7exBRVduvDmGal+hdpT7+KYs0hAGBnus8aHSQYs1Zo6dOGh121QwoaNl 24JopSVt0W/aIWJAEjFOw6O5e0xN9hl8+8owhYvFDCiDVaIv7GqgoPBo7kTpsDyXEUnz anbGwiJor4t/1v5F4XZ3PF6vglPb52cPFPwXAbIl5Qyu3vHETMQBGMeecwdI09z7eESi v6MWI2ucbGltIzxwQGkZhKgbB1Ppq3dvbBovZxz8dA67fbGiU3kVw8rXKRmZ7Jp+edN1 xSoA== X-Forwarded-Encrypted: i=1; AJvYcCW6NsEVvywkeiiqLV5FYnVd3MGQOYZcWcV8qM9s3b/r/Agt6zQN+FnwIWc925hovzLjrZGNRsssbzx2i2c=@vger.kernel.org X-Gm-Message-State: AOJu0YxjdLLK6k9Bzvr0nLF5zZIXAOWZWvnAgzgom3mIDJErz5JFK/cY ma2Hc1VuyWNxge4GcapYQFXvikXkPV5dkYyKOqmWr9zupbBToVNHEZkzhb1EF27mjsbA9mzZeHi M2RLdlw== X-Google-Smtp-Source: AGHT+IHJUITF5zclnwhhjHbh20BakF71z5r6tgDhP0AK9kt5E28tAnRR/N6wBQQHHEoX4jc66xvFWRnCg9Rw X-Received: from qvbkh18.prod.google.com ([2002:a05:6214:5152:b0:6e6:62c7:9f79]) (user=bgeffon job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6214:4119:b0:6d8:99cf:d2db with SMTP id 6a1803df08f44-6e6b01c6a01mr279510756d6.38.1740570501527; Wed, 26 Feb 2025 03:48:21 -0800 (PST) Date: Wed, 26 Feb 2025 06:48:15 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250226114815.758217-1-bgeffon@google.com> Subject: [PATCH] mm: fix finish_fault() handling for large folios From: Brian Geffon To: Andrew Morton Cc: Zi Yan , Kefeng Wang , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Brian Geffon , stable@vger.kernel.org, Baolin Wang , Hugh Dickins , Marek Maslanka Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When handling faults for anon shmem finish_fault() will attempt to install ptes for the entire folio. Unfortunately if it encounters a single non-pte_none entry in that range it will bail, even if the pte that triggered the fault is still pte_none. When this situation happens the fault will be retried endlessly never making forward progress. This patch fixes this behavior and if it detects that a pte in the range is not pte_none it will fall back to setting just the pte for the address that triggered the fault. Cc: stable@vger.kernel.org Cc: Baolin Wang Cc: Hugh Dickins Fixes: 43e027e41423 ("mm: memory: extend finish_fault() to support large fo= lio") Reported-by: Marek Maslanka Signed-off-by: Brian Geffon --- mm/memory.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index b4d3d4893267..32de626ec1da 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5258,9 +5258,22 @@ vm_fault_t finish_fault(struct vm_fault *vmf) ret =3D VM_FAULT_NOPAGE; goto unlock; } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) { - update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); - ret =3D VM_FAULT_NOPAGE; - goto unlock; + /* + * We encountered a set pte, let's just try to install the + * pte for the original fault if that pte is still pte none. + */ + pgoff_t idx =3D (vmf->address - addr) / PAGE_SIZE; + + if (!pte_none(ptep_get_lockless(vmf->pte + idx))) { + update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); + ret =3D VM_FAULT_NOPAGE; + goto unlock; + } + + vmf->pte =3D vmf->pte + idx; + page =3D folio_page(folio, idx); + addr =3D vmf->address; + nr_pages =3D 1; } =20 folio_ref_add(folio, nr_pages - 1); --=20 2.48.1.711.g2feabab25a-goog