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b=t4ETvcgG+DtBZacynsUwUuZzc9gslv6ATrxqYuzM5SYDxYfMTJwJDAsaphiO+bvvO OICL23t3UAxusfjHjVPExe4XEhAXpYpoOdlmD5QaRgAoXbGt/+EU1rx4kdZui/NOSJ oEGXus0qrZn9Mu47YVU9qp2UUNi3kVi2ss0cmW8LbGfxEz4wc4/HRpost/ZSflILHB rD3hTQAh7fiymU01Hv+QWJg80hKaQ4b2uEY3XwFrWPkHiOy5rBU3msgnspXcikMgT2 VMvXXysLtGhQ6LOTSijog2x7X8hA5lpL2caBJ588S+wvIMyL8V7pF3NM5Gfy6SCArG b5FdpcagKWM+A== Date: Fri, 20 Mar 2026 13:35:21 +0200 From: Mike Rapoport To: Pratyush Yadav Cc: Chenghao Duan , pasha.tatashin@soleen.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jianghaoran@kylinos.cn Subject: Re: [PATCH v1 3/3] mm/memfd_luo: use i_size_write() to set inode size during retrieve Message-ID: References: <20260319012845.29570-1-duanchenghao@kylinos.cn> <20260319012845.29570-4-duanchenghao@kylinos.cn> <2vxzqzpebzi2.fsf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2vxzqzpebzi2.fsf@kernel.org> X-Rspam-User: X-Rspamd-Queue-Id: 202DA14000F X-Rspamd-Server: rspam08 X-Stat-Signature: chr5xfhrzmw6xuuprfzytuschs9ietc6 X-HE-Tag: 1774006528-844027 X-HE-Meta: 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 vehJ0aFA ZzvOjgjYhVD6vnDcJHUF2yYcZE1fFamRAna3KKUQf9OMuZ9yOuo/V6QcQQERAlBOUeaWZSaYlCfjbYBq2auI8uUwr0/U5BeN3hx0c1iAUfw3YRzI2tPr1DbxsJLOkw7bNBoqEI+v6c/eN6xuKETINo33iBb7USq8RE6FrJSRlGeLyQZ9E5Cj8W+Au3p1cB4jMuy25+2t8WFXA3LO1hj1gBEFgQUgyGbJFbNX2OTCiLJG5wk36WQG648P5ylI1GbAJximpVY0Unz3qokhKqmxUEstz9DzwycucoupMM2pV8wHqJzg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Mar 20, 2026 at 09:51:01AM +0000, Pratyush Yadav wrote: > On Thu, Mar 19 2026, Chenghao Duan wrote: > > > Use i_size_write() instead of directly assigning to inode->i_size > > when restoring the memfd size in memfd_luo_retrieve(). > > The commit message can be improved. It only explains _what_ the patch > does. Readers can see that by looking at the code. So it just repeats > information that is already there. > > To be fair, for more complex patches explaining the what does make sense > since it might not always be obvious. But what is almost always be a lot > more useful is to explain _why_ this change is made. > > I intentionally assigned i_size directly here. The reason for that being > that no one has access to the inode yet so there is no need for the > smp_store_release() since there won't be racy accesses. So my first > reaction on reading this was to check if I missed some sort of race > condition. I don't see any, but this is exactly the kind of thing the > commit message should say. > > So please, explain why you made this change. The reason can be as simple > as "for consistency", but there should be one so reviewers aren't left > guessing. > > > > > No functional change intended. > > > > Signed-off-by: Chenghao Duan > > --- > > mm/memfd_luo.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/mm/memfd_luo.c b/mm/memfd_luo.c > > index 413df8c75c1d..5e5971f25c68 100644 > > --- a/mm/memfd_luo.c > > +++ b/mm/memfd_luo.c > > @@ -500,7 +500,7 @@ static int memfd_luo_retrieve(struct liveupdate_file_op_args *args) > > } > > > > vfs_setpos(file, ser->pos, MAX_LFS_FILESIZE); > > - file->f_inode->i_size = ser->size; > > + i_size_write(file_inode(file), ser->size); > > For the code change, I am neutral. I don't suppose it makes much of a > difference, but if people think this is cleaner fine by me. I'd also add a comment here explaining that i_size_write() is for consistency :) > > > > if (ser->nr_folios) { > > folios_ser = kho_restore_vmalloc(&ser->folios); > > -- > Regards, > Pratyush Yadav -- Sincerely yours, Mike.