From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta0.migadu.com (out-183.mta0.migadu.com [91.218.175.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9111330678 for ; Fri, 19 Jun 2026 08:03:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781856216; cv=none; b=QKUXtTRmpECCraEnkMsea95XUsaaX97v7SdvaMN012fUYedJ4aQ/P5I13F7rWY0Dll1nEpQdCTQmEMLYHtdws/8czTvTIkTyfj8oigcEzXOG14YjWhuUbLIuz1CBDtqytxv+jXmWGPS0cIMTCxC/c/GIj15L9fDqAdnU2MhM0iM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781856216; c=relaxed/simple; bh=ztgvt3KFrUzJ9sy/un5zYu773skg9zw4JRLlJ1TpoY0=; h=Mime-Version:Content-Type:Date:Message-Id:Cc:Subject:From:To: References:In-Reply-To; b=HgCL1J7Hu7dJl+uZG2B+M8Nn50SYSv+idsOH/yArS18Z1LY0rbVcHtdcggTq9GNXWSHEnx/Gf2Ga5jwx4774Cn7sd2KaA9577bLFj732pLxR2xssZrNR6z8B1e1mmXwrppA2I03gC4KVOBKTMH7j1Mwi2Bb66OT2OW6+4v4y1p0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=JO24wKCZ; arc=none smtp.client-ip=91.218.175.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="JO24wKCZ" Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1781856211; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=97ALfhxEHKnHr+DmTHdJ5AlydQr7RUIpXUMAyaq3tCI=; b=JO24wKCZF5d/OU6egxMZuPUk6dgIJvBGm4v0uD7IArIJp9pyn/5XcsAHDty9wVgahfTxAv wA4cxqUQmxO2lMudPiLf1Y+W6W9OXOpiiN+fOvhlTVMSvM6HZAgFEnVbVgZX5rBmdGBZgV ych8oKJROkfLPyWkoMLLClVHFy8WIKA= Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 19 Jun 2026 08:03:13 +0000 Message-Id: Cc: "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" 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 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.