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Petersen" , linux-block@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/3] slab, block: generalize bvec_alloc_gfp Message-ID: References: <20251023080919.9209-1-hch@lst.de> <20251023080919.9209-2-hch@lst.de> <20251027064728.GA13145@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251027064728.GA13145@lst.de> X-Stat-Signature: ocwmo6rmifurog3nwrsszfy59bwg745u X-Rspamd-Queue-Id: 6930A180004 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1761570554-791344 X-HE-Meta: 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 n+EifDeI ZRlCTMnrvUnTqvcW4/FblzY6IKbsbDVb60uDGC7t1+Kbf0AzU1IpyBGI4HGNrjHj+hzJNIQaKjwUJ5QWVYaDasEugpI9DRnR7fl1xNqaFF4KUQYnRvbjIdTTlfZpnGyQ4iChb93Y2d79SYyhK9IQh6mn8FBMPGHPm28JKBPXVyfwHmjUO8s6r+pTRunUwcqifE3m5ibXMRPTPgHienEjJmEEr8xTQX/B76Ge1JDXWpbUqo9OhM+OSvEQn8g+fdx17ZQwoQ1UlSpPLPxe81LKBV+RU+d7KaodKhC09OOLO8r74tSk= 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, Oct 27, 2025 at 07:47:28AM +0100, Christoph Hellwig wrote: > On Sun, Oct 26, 2025 at 09:19:27PM +0000, Matthew Wilcox wrote: > > it's quite different. I am by no stretch of the imagination a GFP > > flags expert, but it seems to me that we should make the two the same > > since they're both "try to allocate and we have a fallback if > > necessary". I suspect kvmalloc() is called with a wider range of > > GFP flags than bvec allocation is, so it's probably better tested. > > > > Is there a reason _not_ to use the kvmalloc code for bvec allocations? > > It's using a dedicated slab cache, which makes sense for such a frequent > and usually short-lived allocation. We also don't use vmalloc backing > ever at the moment. That's not what I meant. What I was proposing was: +static inline gfp_t try_alloc_gfp(gfp_t gfp) +{ + gfp |= __GFP_NOWARN; + if (!(gfp & __GFP_RETRY_MAYFAIL)) + gfp &= ~__GFP_DIRECT_RECLAIM; + gfp &= ~__GFP_NOFAIL; + + return gfp; +}