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Mon, 08 Jun 2026 18:14:54 -0700 (PDT) Date: Tue, 9 Jun 2026 01:14:53 +0000 From: Pasha Tatashin To: Mike Rapoport Cc: Pasha Tatashin , linux-kselftest@vger.kernel.org, shuah@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, skhan@linuxfoundation.org, linux-doc@vger.kernel.org, jasonmiu@google.com, linux-kernel@vger.kernel.org, corbet@lwn.net, ran.xiaokai@zte.com.cn, kexec@lists.infradead.org, pratyush@kernel.org, graf@amazon.com Subject: Re: [RFC v1 0/9] kho: granular compatibility and header decoupling Message-ID: References: <20260605033235.717351-1-pasha.tatashin@soleen.com> <178083348872.1648214.17778188633648887952.b4-review@b4> <178091437240.1648214.10761111570005003901.b4-reply@b4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 512F640004 X-Rspam-User: X-Stat-Signature: njxk6jzpzjwy1agxp1tk3o3sprxj4ndc X-Rspamd-Server: rspam09 X-HE-Tag: 1780967696-242957 X-HE-Meta: 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 MXXUPyX3 dIHLR/U9UqHHMujrgJXyZ6zT2ei/+reMAb0v/YRnxbAZ6l6fuVk8/x1fCPzOSNPm7w4L+9wElA1nBIIb8Q7gVrgFMVIH6ovflkXA4lN+mZpfDRqlm6uS5pXqvSlMwqns3engFYZa2vCFE8kBvNplY/ouNAn/fQUJfv7edkU0W4lPIhOKk+1yVpOaqDFw2dqEUmlMkF+fWAK7zWBmpOPHxJSWeLpzsHcIhDQvOFN0xBkRczxfEm/fg2hLju3Gxzx1QY8nsDln4KZDEXpLjACnAzxBbCjxqmYOOeWZ6azugKTkQ0RI673Vry+OcQQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 06-08 21:11, Mike Rapoport wrote: > On Mon, Jun 08, 2026 at 04:12:56PM +0000, Pasha Tatashin wrote: > > On 06-08 13:26, Mike Rapoport wrote: > > > On 2026-06-07 13:43:09+00:00, Pasha Tatashin wrote: > > > > Keeping all of that in a single KHO file is the wrong approach and goes > > against how other logically separated subsystems in Linux are organized > > (e.g., mm/vmap.c, mm/vmalloc.c, etc.). Yes, there are some messier > > places in the kernel as well, but keeping this in its own dedicated > > kho_vmalloc.c file makes complete sense to me. > > Either I hallucinated or b4 ate a paragraph from my reply ;) > > Regarding the code movement > - splitting radix tree makes perfect sense to me, just the documentation > part needs more care than mechanical move Agreed. I'll also pay closer attention to the documentation. > - I'm fine with abi/vmalloc.h, presuming KHOSER_PTR() is not part of it Yes, I will move KHOSER_PTR() to the shared compat.h in v2 so it's not tied to vmalloc. > - I can live with kho_vmalloc.c although I still consider it unnecessary > churn Appreciate it. > - I'm against moving vmalloc APIs from kexec_handover.h because they are > very close in nature to folio and pages. I don't see core KHO as > responsible for preserving physically contiguous ranges but rather as > preserving allocations. Not sure we'll ever support kmalloc(), but still. That is a very reasonable compromise. I am fine with keeping the consumer-facing function declarations in kexec_handover.h so they remain grouped with folios and pages. > > However, overall enforcing the use of KHOSER is unrelated to this work. > > I have my own thoughts on this, and perhaps with proper versioning, > > using KHOSER_PTR everywhere would be appropriate, but let's keep that as > > a separate work. > > This is a separate work, indeed. But regardless of the versioning it's > already better than plain u64 because it provides type safety. Agreed. Thanks! Pasha