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From: "Brendan Jackman" To: "Hao Ge" , "Brendan Jackman" , "Andrew Morton" , "Vlastimil Babka" , "Suren Baghdasaryan" , "Michal Hocko" , "Johannes Weiner" , "Zi Yan" , "Muchun Song" , "Oscar Salvador" , "David Hildenbrand" , "Lorenzo Stoakes" , "Liam R. 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" References: <20260617-alloc-trylock-v1-1-83fd7858832e@google.com> <692d9bfb-66ee-448c-942f-a26c07a19f61@linux.dev> In-Reply-To: <692d9bfb-66ee-448c-942f-a26c07a19f61@linux.dev> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 346FFA0005 X-Stat-Signature: pgu5tgtfsb7paeb36bmosre8fdt46gd8 X-HE-Tag: 1781856214-83104 X-HE-Meta: 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 kgTxi9lt za1tOlt57rZeRideApkRNchZzTJdUW3UnIISxCn+cNNuPMeQQvOUEetJSOEXMPPlF1iIbLhpsfVNTZzjE8PyqXO0KtGfA23e914+wlq3v1MRoqpDvCVt50v4vyzfNaO8PQzH9sTRXjkDboAIo3HZcx8tdoO8NWmkFOZDYwpyv1ePRe0iwSJ0rVDLJPggsthDZYe5+BzD0JLnlpK5Lwu21Zn8m94X8fnIKLSZ2+RRSES9ZQDWLV69QV2Ei1v1gUUyeQFyZuwCKVeoTZ4qKN+xoTzbtmMpBW3TL5yteZ0pO44pRfZHZmq543oOJUZN+nDteHSsjGJoDYaxYzGGedk6q2en3GxwtXGoMESi7l5qXeTFrYQA= 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 6:56 AM UTC, Hao Ge wrote: > Hi Brendan > > > On 2026/6/17 23:29, Brendan Jackman wrote: >> Currently the core allocator code is controlled by ALLOC_NOLOCK, but the >> 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 only >> 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 to >> 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, an= d >> 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. >> >> 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. > > > If so, I believe we could generalize this further. > > Under the current logic, |__alloc_pages_slowpath| cannot access the=20 > alloc_flags > passed down from upper-level callers. > As I discussed in another thread, we can introduce a new alloc_flags to > replace the |__GFP_NO_CODETAG| (|__GFP_NO_OBJ_EXT|) GFP flag. > This newly added flag needs to be propagated along the entire call > chain down to |prep_new_page|, which means |__alloc_pages_slowpath| also= =20 > has to > handle this flag accordingly. > > I'm wondering if we could introduce a caller_alloc_flags field within=20 > struct alloc_context > to handle alloc_flags that need to persist throughout the entire page=20 > allocation cycle, when such flags exist. > I'm sure others will have more appropriate solutions. Yeah totally, this is exactly how I imagined this evolving.