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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" , "Alexei Starovoitov" , "Harry Yoo (Oracle)" , "Gregory Price" , , , Subject: Re: [PATCH] mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof() X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Brendan Jackman" References: <20260617-alloc-trylock-v1-1-83fd7858832e@google.com> <2399b3ad-4eac-4a14-94c3-27e9f07972a1@kernel.org> <45fcc57a-ec8d-46d6-9c28-065d001c081f@linux.dev> In-Reply-To: <45fcc57a-ec8d-46d6-9c28-065d001c081f@linux.dev> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 7D6CD180004 X-Stat-Signature: qbzwzf87gyjc3ye5x7iq8dcbp17h8rsy X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1781870265-904722 X-HE-Meta: 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 31RXOxpx zi+Gkspnv82j7SZiVOtStu1lZvnRwXqt3hq/zS96mwjzqcYbj9QD5gD5lvAKWBk4bfc1Ti35OfexdwLwI0m69K4/x1rBraZoX8fCMMlCd1z5jReAOElXekm4r06rRCqVuXywm2R1AfeZLfikoaq8Wt2M8oSamoHCbKaz7vtp+IW1ImhrMbcXeRgwYpzajJolT+JbnSF8IcGHambaqH6oZAt5pS8qG0EeQ7cWvtFMyXaV+9WLi9sz8f1+R3yNnbKRBmvYYxxuAQlYgp60oAztA112k+kyxpd4IHeOjPyxHryUqpZPPkeM6p4IX3phX/QI94QKuj3xHu1AeMNEoXo7TRRgOixkhkDF2KYZ0NhokoK1H8+1WOIno38F1mEDAer0l/kbHNqG4u3WffqBGytLZdHhX3bwq8xbzTHqd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu Jun 18, 2026 at 2:22 AM UTC, Hao Ge wrote: > > On 2026/6/18 01:14, Brendan Jackman wrote: >> On Wed Jun 17, 2026 at 4:49 PM UTC, Suren Baghdasaryan wrote: >>> On Wed, Jun 17, 2026 at 9:39=E2=80=AFAM Vlastimil Babka (SUSE) >>> wrote: >>>> +Cc Alexei >>>> >>>> On 6/17/26 17:29, Brendan Jackman wrote: >>>>> Currently the core allocator code is controlled by ALLOC_NOLOCK, but = the >>>> It's not, it's ALLOC_TRYLOCK! Thanks for proving that we need to renam= e it >>>> to ALLOC_NOLOCK: >>>> >>>> https://lore.kernel.org/all/DJ9QPTO2WXNB.10E88ZHWRDHB0@gmail.com/ >>>> >>>> So you just won the job to do the rename :) I think it should be done = before >>>> this patch, so that the new usages and other _trylock names introduced= here >>>> can be done as _nolock outright. >> Ack. I'll aim to send that tomorrow once Sashiko has caught up. >> >>>>> main entry point function is significantly different from the normal >>>>> __alloc_frozen_pages_nolock(), this is tiring when reading the code. >>>>> >>>>> Plumb the ALLOC_NOLOCK control one layer up in the call stack: create >>>>> an alloc_flags argument to __alloc_frozen_pages_nolock() (which is on= ly >>>>> exposed to mm/) and then turn the nolock variant into a thin wrapper >>>>> that just sets that flag (as well as handling NUMA_NO_NODE, similar t= o >>>>> how some of the wrappers in gfp.h do). >>>>> >>>>> Rationale that this doesn't change anything: >>>>> >>>>> 1. Simple bits: A bunch of the nolock-specific handling is just moved= to >>>>> the new alloc_order_allowed(), alloc_trylock_allowed() and >>>>> gfp_trylock. >>>>> >>>>> 2. __alloc_frozen_pages_noprof() has some extra logic that wasn't >>>>> previously in the nolock variant: >>>>> >>>>> a. Application of gfp_allowed_mask; this only affects early boot,= and >>>>> only flags that affect the slowpath get changed here. >>>>> >>>>> b. Application of current_gfp_context() - also only affects the >>>>> slowpath >>>>> >>>>> 3. The slowpath itself: this is now just explicitly skipped under >>>>> !ALLOC_TRYLOCK. >>>> I'll have to ponder it more closely. >>>> >>>>> Ulterior motive: adding an alloc_flags arg to the allocator's >>>>> mm-internal entrypoint can later be used to do more allocation >>>>> customisation without needing to create new GFP flags. >>>> Ack. >>> I think this change might also help us in removing __GFP_NO_CODETAG >> Nice, this actually looks trivial? I can probably just tack it onto the >> v2 for this patch/series. >> >>> introduced in [1] and being the only user of __GFP_NO_OBJ_EXT once >>> Vlastimil's patchset removing other __GFP_NO_OBJ_EXT users lands. >>> CC'ing Hao as he is brainstorming ways to remove __GFP_NO_CODETAG, and >>> this might be the answer. > > > Hi Brendan, Suren, > > Thanks for CC'ing me, Suren. This is indeed a viable approach > > and I believe it brings us one step closer to removing > > __GFP_NO_CODETAG entirely. > > > Brendan, I'd actually put together a rough local implementation > > earlier with mostly the same core idea as yours, and this change > > would indeed be minimal based on your patch. > > Thanks a lot for being interested in tacking this into your v2 patch seri= es. Oh, I just took a look and it's a bit more fiddly than I thought because alloc_tag.c is actually in lib/ not mm/.=20 How did you tackle that, can you share your implementation? It would be nice if we can avoid exposing alloc_flags in gfp.h.