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Howlett" , "Mike Rapoport" , "Matthew Brost" , "Joshua Hahn" , "Rakie Kim" , "Byungchul Park" , "Ying Huang" , "Alistair Popple" , "Hao Li" , "Christoph Lameter" , "David Rientjes" , "Roman Gushchin" , "Sebastian Andrzej Siewior" , "Clark Williams" , "Steven Rostedt" Subject: Re: [PATCH v3 15/16] mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Brendan Jackman" References: <20260629-alloc-trylock-v3-0-57bef0eadbc2@google.com> <20260629-alloc-trylock-v3-15-57bef0eadbc2@google.com> In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 7o5no7wrgzdxygckhqr9nwexw3h4jpn1 X-Rspam-User: X-Rspamd-Queue-Id: 05A8A4000C X-Rspamd-Server: rspam02 X-HE-Tag: 1782820912-494882 X-HE-Meta: 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 TGrd1ogO gw98skxP4dYgnyMOOEmZCzGe789oRQGdNYpgDNH9Uid4uTuOwxZxBm6c/uvIvKwrZT3qiKCrD9OYdW0XyMkgu8S4FO8lZYZhdWzWdOw5GLdpbQvwL0rFFqBySvOs8aXq3AtC7BEidNeevg53IE5O6mKqVvS0tuI0EbNVzoWfO309c9u3c8xHB5E3wEAPCTOAwvZytLbaGjfod8Fb35I/KhYwRvF3fENwcG4gsJqfbf5vwYb6wu/LyPa4E7BpB8eHT6dSl99H0CLI5EJYZQr8RaN2gt7sgUkCzPZkr0dWrmB0mR0/OkWxd1KuaePbNwf0+nWTdfdkR2RWVWHaug7QEXikI9WkG5kCebBZhDBcRSNE7q4o= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue Jun 30, 2026 at 1:55 AM UTC, Hao Ge wrote: >> +/* >> + * Skip early PFN recording for a page allocation. Used by >> + * __alloc_tag_add_early_pfn() to avoid recursion when allocating pages= for the >> + * early PFN tracking list itself. >> + * >> + * Codetags of the pages allocated with __GFP_NO_CODETAG should be >> + * cleared (via clear_page_tag_ref()) before freeing the pages to preve= nt >> + * alloc_tag_sub_check() from triggering a warning. >> + */ > > > I originally wrote this lengthy comment because the logic lives inside=20 > alloc_tag.c. > > I wanted to document all the context to avoid confusion when revisiting= =20 > this code later on. > > We've since replaced __GFP_NO_CODETAG with ALLOC_NO_CODETAG, a generic=20 > alloc_flags bit defined in page_alloc.h. > > The original long comment is no longer accurate: > > Given that, I suggest updating it to the following: > > /* > > =C2=A0* Avoid alloc_tag recursion for internal allocations. > > =C2=A0* Callers must clear_page_tag_ref() before > =C2=A0* freeing to avoid warnings from alloc_tag_sub_check(). > > =C2=A0*/ Thanks for the context, pasting this in for v4!