From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BDA7E2D9484; Mon, 21 Sep 2026 04:12:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789963930; cv=none; b=coauPwwZ4/rZ4YzR0xN/7SOyE7baAUH0vdw6Hu0dFnx8+iSy2yrrOhoKjTwBJ3NbSvbUA9/iEmRA81O6llFmVna6VOX0J9RApzA/9G9S1T6HGTxHKJKpqECWDPvbcdkn85YeePboN/KDW6xbTBxVzq4P5151DrQ+iQiCkRVL2rM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789963930; c=relaxed/simple; bh=JQteEG8aEomBNPZ/3WuvISiRCdp0U1U8G8bw6F46X/c=; h=Date:To:From:Subject:Message-Id; b=uKRnnl0M9+Niwuv1lt7zQQ9FzRlAHqkGISiYHpK837jBv4rP3VQEphVJE0bBR6x4fB8w6bpQPvjagGV0A7dIfVU3b9HDoYj3chtK3H6Yo+NntGkwj04ygfPSGwYW2RDKLix0uoMveYzGSSJz5gOviYduQgYjiyGLffCnkE4p99g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=ekcbdR9o; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="ekcbdR9o" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EAB21F000FF; Mon, 21 Sep 2026 04:12:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789963929; bh=0fP/BttSWFVif+inM5k3TC5NNn6OzY5ZqIHsXFmdegE=; h=Date:To:From:Subject; b=ekcbdR9o4ke9VS5Cf6us9K5fIzaDACHZEbRoJaXcXwxZZJ0g3ssanRzSFKdS53Dhf 1F6AFKOD+U8tQIQayU2UdlQNzwtt9Kzyc3ByTBSba+J1Z2NSZE9Qd47NJsBMtCxt9f 3Wc15ln3/9hpKZfygEwoYu7ufQyPafeKqzqqoC4Y= Date: Sun, 20 Sep 2026 21:12:08 -0700 To: mm-commits@vger.kernel.org,stable@vger.kernel.org,peterx@redhat.com,jhubbard@nvidia.com,jgg@ziepe.ca,david@kernel.org,gregkh@linuxfoundation.org,akpm@linux-foundation.org From: Andrew Morton Subject: [obsolete] mm-gup-honour-foll_pin-in-nommu-__get_user_pages_locked.patch removed from -mm tree Message-Id: <20260921041209.3EAB21F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/gup: honour FOLL_PIN in NOMMU __get_user_pages_locked() has been removed from the -mm tree. Its filename was mm-gup-honour-foll_pin-in-nommu-__get_user_pages_locked.patch This patch was dropped because it is obsolete ------------------------------------------------------ From: Greg Kroah-Hartman Subject: mm/gup: honour FOLL_PIN in NOMMU __get_user_pages_locked() Date: Thu, 23 Apr 2026 16:28:04 +0200 The !CONFIG_MMU implementation of __get_user_pages_locked() takes a bare get_page() reference for each page regardless of foll_flags: if (pages[i]) get_page(pages[i]); This is reached from pin_user_pages*() with FOLL_PIN set. unpin_user_page() is shared between MMU and NOMMU configurations and unconditionally calls gup_put_folio(..., FOLL_PIN), which subtracts GUP_PIN_COUNTING_BIAS (1024) from the folio refcount. This means that pin adds 1, and then unpin will subtract 1024. If a user maps a page (refcount 1), registers it 1023 times as an io_uring fixed buffer (1023 pin_user_pages calls -> refcount 1024), then unregisters: the first unpin_user_page subtracts 1024, refcount hits 0, the page is freed and returned to the buddy allocator. The remaining 1022 unpins write into whatever was reallocated, and the user's VMA still maps the freed page (NOMMU has no MMU to invalidate it). Reallocating the page for an io_uring pbuf_ring then lets userspace corrupt the new owner's data through the stale mapping. Use try_grab_folio() which adds GUP_PIN_COUNTING_BIAS for FOLL_PIN and 1 for FOLL_GET, mirroring the CONFIG_MMU path so pin and unpin are symmetric. While at it, don't return NULL pointers in the page array, as this is really not expected for GUP users; instead, just fail and return -EFAULT. [david@kernel.org: changelog update] https://lore.kernel.org/e9c5cf89-fa4c-4b83-ae70-9d3c72542ee9@kernel.org Link: https://lore.kernel.org/2026042303-vendor-outright-b9d2@gregkh Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andrew Morton Acked-by: David Hildenbrand (Arm) Assisted-by: David Hildenbrand Reported-by: Anthropic Assisted-by: gkh_clanker_t1000 Cc: Jason Gunthorpe Cc: John Hubbard Cc: Peter Xu Cc: --- mm/gup.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/mm/gup.c~mm-gup-honour-foll_pin-in-nommu-__get_user_pages_locked +++ a/mm/gup.c @@ -1987,6 +1987,7 @@ static long __get_user_pages_locked(stru struct vm_area_struct *vma; bool must_unlock = false; vm_flags_t vm_flags; + int ret, err = -EFAULT; long i; if (!nr_pages) @@ -2022,8 +2023,14 @@ static long __get_user_pages_locked(stru if (pages) { pages[i] = virt_to_page((void *)start); - if (pages[i]) - get_page(pages[i]); + if (!pages[i]) + break; + ret = try_grab_folio(page_folio(pages[i]), 1, foll_flags); + if (unlikely(ret)) { + pages[i] = NULL; + err = ret; + break; + } } start = (start + PAGE_SIZE) & PAGE_MASK; @@ -2034,7 +2041,7 @@ static long __get_user_pages_locked(stru *locked = 0; } - return i ? : -EFAULT; + return i ? : err; } #endif /* !CONFIG_MMU */ _ Patches currently in -mm which might be from gregkh@linuxfoundation.org are