From: "Michał Mirosław" <emmir@google.com>
To: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Andrei Vagin <avagin@gmail.com>, Peter Xu <peterx@redhat.com>,
David Hildenbrand <david@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Danylo Mocherniuk <mdanylo@google.com>,
Paul Gofman <pgofman@codeweavers.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Mike Rapoport <rppt@kernel.org>, Nadav Amit <namit@vmware.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Shuah Khan <shuah@kernel.org>,
Christian Brauner <brauner@kernel.org>,
Yang Shi <shy828301@gmail.com>, Vlastimil Babka <vbabka@suse.cz>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
Yun Zhou <yun.zhou@windriver.com>,
Suren Baghdasaryan <surenb@google.com>,
Alex Sierra <alex.sierra@amd.com>,
Matthew Wilcox <willy@infradead.org>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Axel Rasmussen <axelrasmussen@google.com>,
"Gustavo A . R . Silva" <gustavoars@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
Greg KH <gregkh@linuxfoundation.org>,
kernel@collabora.com
Subject: Re: [PATCH v19 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs
Date: Wed, 21 Jun 2023 15:29:20 +0200 [thread overview]
Message-ID: <CABb0KFHpE+jJH0MmxZTFaQ9FNFNUnJcnnv7sSGDYqDqqB_FRqw@mail.gmail.com> (raw)
In-Reply-To: <1c1beeda-ceed-fdab-bbf5-1881e0a8b102@collabora.com>
On Wed, 21 Jun 2023 at 08:35, Muhammad Usama Anjum
<usama.anjum@collabora.com> wrote:
> On 6/20/23 11:03 PM, Andrei Vagin wrote:
> ...
> >> +struct pagemap_scan_private {
> >> + struct page_region *vec_buf, cur_buf;
> >> + unsigned long long vec_buf_len, vec_buf_index, max_pages, found_pages, flags;
> >
> > should it be just unsigned long?
> These internal values are storing data coming from user in struct
> pm_scan_arg in which all variables are 64 bit(__u64) explicitly. This is
> why we have unsigned long long here. It is absolutely necessary.
vec_buf_len and vec_buf_index can only have values in 0..512 range.
flags has only a few lower bits defined (this is checked on ioctl
entry) and max_pages can be limited to ULONG_MAX. Actually putting `if
(!max_pages || max_pages > ULONG_MAX) max_pages = ULONG_MAX` would
avoid having to check !max_pages during the walk.
Best Regards
Michał Mirosław
next prev parent reply other threads:[~2023-06-21 13:29 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-15 14:11 [PATCH v19 0/5] " Muhammad Usama Anjum
2023-06-15 14:11 ` [PATCH v19 1/5] userfaultfd: UFFD_FEATURE_WP_ASYNC Muhammad Usama Anjum
2023-06-15 14:11 ` [PATCH v19 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs Muhammad Usama Anjum
2023-06-15 16:40 ` kernel test robot
2023-06-17 6:39 ` Andrei Vagin
2023-06-19 6:06 ` Muhammad Usama Anjum
2023-06-20 11:19 ` Muhammad Usama Anjum
2023-06-21 6:42 ` Andrei Vagin
2023-06-21 7:02 ` Muhammad Usama Anjum
2023-06-20 18:03 ` Andrei Vagin
2023-06-21 6:34 ` Muhammad Usama Anjum
2023-06-21 13:29 ` Michał Mirosław [this message]
2023-06-22 9:59 ` Muhammad Usama Anjum
2023-06-21 19:45 ` Andrei Vagin
2023-06-22 10:20 ` Muhammad Usama Anjum
2023-06-23 9:44 ` Michał Mirosław
2023-06-15 14:11 ` [PATCH v19 3/5] tools headers UAPI: Update linux/fs.h with the kernel sources Muhammad Usama Anjum
2023-06-15 14:11 ` [PATCH v19 4/5] mm/pagemap: add documentation of PAGEMAP_SCAN IOCTL Muhammad Usama Anjum
2023-06-15 14:11 ` [PATCH v19 5/5] selftests: mm: add pagemap ioctl tests Muhammad Usama Anjum
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