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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmcbG-00000002KpW-3m92; Tue, 19 Mar 2024 16:46:06 +0000 Date: Tue, 19 Mar 2024 16:46:06 +0000 From: Matthew Wilcox To: Kairui Song Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] mm/filemap: return early if failed to allocate memory for split Message-ID: References: <20240319092733.4501-1-ryncsn@gmail.com> <20240319092733.4501-2-ryncsn@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240319092733.4501-2-ryncsn@gmail.com> X-Rspamd-Queue-Id: 46F2D1A0011 X-Rspam-User: X-Stat-Signature: rkp7r69diahfjtfgya9yh3yw5bngepdb X-Rspamd-Server: rspam03 X-HE-Tag: 1710866774-835799 X-HE-Meta: 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 rsUlXzOA 0VKD2sihHXAvetJc4G6ObhXgcmlKKMAuIoB+GmRQISZNVgJitDmOWRWBq9XknJ0ReFd7IVKu3RYrQJnqso56dIXCwXvxEk6oDNVKDuhNIDP814nXwRAMl09GQBoLxVrZcNGCfO+huGaID4UQTWfNJMi0RzjZc98+S8sXFTvCV+RMwI/bfLRVeqYfGyF+sGOPS87L5BM5FFtEd88ICFjT4/xaZmWeknVcBwSKLPJ9vV66NXI/fv51X/MTvBVJ7esCRgZsf X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 19, 2024 at 05:27:30PM +0800, Kairui Song wrote: > From: Kairui Song > > xas_split_alloc could fail with NOMEM, and in such case, it should abort > early instead of keep going and fail the xas_split below. > > Signed-off-by: Kairui Song The usual way of programming with an xa_state is to not do any error handling; the xas_ functions check for error and become no-ops, so we only have to check at the end. I think this case is worth making an exception for because we avoid acquiring/releasing the lock. Not that we should be getting ENOMEM very often; we only allocate about 8 nodes usually and we get 7 nodes/page. Acked-by: Matthew Wilcox (Oracle) > mm/filemap.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 7437b2bd75c1..f07ea0b97698 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -880,9 +880,12 @@ noinline int __filemap_add_folio(struct address_space *mapping, > unsigned int order = xa_get_order(xas.xa, xas.xa_index); > void *entry, *old = NULL; > > - if (order > folio_order(folio)) > + if (order > folio_order(folio)) { > xas_split_alloc(&xas, xa_load(xas.xa, xas.xa_index), > order, gfp); > + if (xas_error(&xas)) > + goto error; > + } > xas_lock_irq(&xas); > xas_for_each_conflict(&xas, entry) { > old = entry; > -- > 2.43.0 >