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Carvalho" Cc: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, djwong@kernel.org, Dave Chinner , hch@lst.de, willy@infradead.org Subject: Re: [PATCH v2] mm: Fix error handling in __filemap_get_folio() with FGP_NOWAIT Message-ID: <20250224141744.GA1088@lst.de> References: <20250224081328.18090-1-raphaelsc@scylladb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250224081328.18090-1-raphaelsc@scylladb.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspam-User: X-Rspamd-Queue-Id: DB8F74000B X-Rspamd-Server: rspam12 X-Stat-Signature: 4ym34gw8wjkyaji9r8pbqbm4fohesq9f X-HE-Tag: 1740406670-713122 X-HE-Meta: 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 xKVWBbds iSkYgnPTMFs5skTEo/XJ8aUwjrnlF9rSMjaPWGqZx6RsbknerFk7tP+OcON/Qlys/NwPocyPoIyTeZvHrFHfB7xceaGxlwoQfVlKSVy8fRTcACcVkuoqL4+UP2A== 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 Mon, Feb 24, 2025 at 05:13:28AM -0300, Raphael S. Carvalho wrote: > + if (err) { > + /* Prevents -ENOMEM from escaping to user space with FGP_NOWAIT */ > + if ((fgp_flags & FGP_NOWAIT) && err == -ENOMEM) > + err = -EAGAIN; > return ERR_PTR(err); I don't think the comment is all that useful. It's also overly long. I'd suggest this instead: /* * When NOWAIT I/O fails to allocate folios this could * be due to a nonblocking memory allocation and not * because the system actually is out of memory. * Return -EAGAIN so that there caller retries in a * blocking fashion instead of propagating -ENOMEM * to the application. */