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Howlett" , Alice Ryhl , Andrew Ballance , linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org, Lorenzo Stoakes , Pranjal Shrivastava , Will Deacon , Suzuki K Poulose , Neil Armstrong , Mostafa Saleh , Balbir Singh , Suren Baghdasaryan , Marco Elver , Dmitry Vyukov , Alexander Potapenko , Shuah Khan , Dev Jain , Brendan Jackman , Puranjay Mohan , Santosh Shukla , Wyes Karny , Sudeep Holla Subject: Re: [PATCH RFC 00/12] mm/vmalloc: migrate vmap_area indexing from rb-tree to maple-tree Message-ID: References: <20260613-vmalloc_maple-v1-0-0aa740bb944b@oss.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1848E40004 X-Stat-Signature: jqw9o54cwb79o3ngx1ktw4ujddueydhb X-HE-Tag: 1782483332-456952 X-HE-Meta: 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 DVskzcBl QrZGEse4DIQGZUeo2kNet8KV6HsuVsUcjkES3KcQANragNoJupff2ULpK78kG5Ip84PaG83BN9haYCAKnJibuyHAgPjuZWzWtRS6xhxE4kf/B477AXABlFVuBaD5aHQpBVZL/3b9//qMueiXlKNOdPZLiOxnfDhVylYEzN2BzKbF/u2Yb/P7CSHjXyngXG49D5isDaCdV2tvOxXlL8Xv2HaCWT53bvFYEdw3XwX5oW6ruFH5Ls29CgKB/eE6Bu4wDYjkgqKL7OdSN3Wij0KaVuSf/fq3BxsBua2lDIyTjgcZQlOUozGytbcwYpAdCGD+TgX6rZa/VoBIJPUXWWvh26DTVc2w4IlflbOX255MKJyNPj4KWTEnE80YGSA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 26, 2026 at 04:17:08PM +0530, Pranjal Arya wrote: > I am planning to have following approach on this: > > 1. mas_preallocate(GFP_NOWAIT | __GFP_NOWARN) + mas_store_prealloc > will be fast path. The preallocate attempt will be non sleeping and, > if it succeeds, the subsequent store won't require allocation. > > 2. mas_store_gfp(GFP_ATOMIC | __GFP_NOWARN) fallback: if > preallocate fails (rare but possible under memory pressure), > GFP_ATOMIC will make a non sleeping allocation attempt inline. This isn't how you're supposed to use the maple tree. The intent is that it's protected by its internal spinlock, and so it can drop the lock to allocate memory if it needs to in order to balance the tree. If the user needs to also use that spinlock to protect other things, that's allowed.