From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B970634CDD for ; Wed, 4 Feb 2026 21:01:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770238909; cv=none; b=Cscu+nfQgfgk02IsZGoSpqZ7p7j4EV0zFxegYDpqORoMOu7gY6f7XQURKO48fmYMcrBTgmWm7oEBncEa01GwdzLN4sjA95+RyA+opDfpiPtgFViZ3TsWyIfmotKqsu1qsJS2h2LNnhDtfof5KK1bUCi9cfOETXimHR+ro+OSRMM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770238909; c=relaxed/simple; bh=jp2KfloYw+uC2B4Pxh+HiUCTQy7uOAAaMHvJN6AaS6c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rQ8X3YonvCiOQrREsc0+mVvC/KxamM7+tTsQIGOg31DwwScQBE5V6VFJAtggXSXaHU5JeWiCXJ6zRJW4vqT5BHGcw0mVjw7MC4UNApSRHs02FsM69sQXT3RIEv0rUo28Er9dlcRRffVfAKopd8oKkvfZftZQGmMVzogtcW+ECH8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Vzrnjuj/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Vzrnjuj/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA2C9C4CEF7; Wed, 4 Feb 2026 21:01:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770238909; bh=jp2KfloYw+uC2B4Pxh+HiUCTQy7uOAAaMHvJN6AaS6c=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Vzrnjuj/OhJlTXjtTS+zXd6lBLI3Hiy4cjnZ1JFzAV4OwNr4aBpV5r5gxMCWDXb7W yJZoVMfN6LFBlWkgImX9+f1eXNpte8okcFJ3D3N+5VjQMXdPFA0SUdhXMvaO1/KNYY q621/QIUEvMNKxbMZKdfnR0fpMtFX/bK+sKRFWX0ZOjj/dNfeKn5QT4rb5rc5gjDmE x6xjMVdUETf+K3mbOGTED080SE3lbocDvqPiMVIc5c/ljKPAIso7z0+XVkLqaTYhNU m7wCg7fEA1IdNGDk/yZ7X0lvogdWdcOrE563hP1IUoRgTQC8hjQJySuQznONrj74q9 s7shtKCW4HvEQ== Message-ID: <9206a7c4-bf88-4138-b8af-961625a82439@kernel.org> Date: Wed, 4 Feb 2026 22:01:42 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: folio_zero_user: open code range computation in folio_zero_user() To: Ankur Arora , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Cc: akpm@linux-foundation.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, mjguzik@gmail.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, willy@infradead.org, raghavendra.kt@amd.com, chleroy@kernel.org, ioworker0@gmail.com, lizhe.67@bytedance.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, kernel test robot References: <20260107072009.1615991-9-ankur.a.arora@oracle.com> <20260128185943.2397128-1-ankur.a.arora@oracle.com> From: "David Hildenbrand (arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/28/26 19:59, Ankur Arora wrote: > riscv64-gcc-linux-gnu (v8.5) reports a compile time assert in: > > r[2] = DEFINE_RANGE(clamp_t(s64, fault_idx - radius, pg.start, pg.end), > clamp_t(s64, fault_idx + radius, pg.start, pg.end)); > > where it decides that pg.start > pg.end in: > clamp_t(s64, fault_idx + radius, pg.start, pg.end)); > > where pg comes from: > const struct range pg = DEFINE_RANGE(0, folio_nr_pages(folio) - 1); > > That does not seem like it could be true. Even for pg.start == pg.end, > we would need folio_test_large() to evaluate to false at compile time: > > static inline unsigned long folio_nr_pages(const struct folio *folio) > { > if (!folio_test_large(folio)) > return 1; > return folio_large_nr_pages(folio); > } > > Workaround by open coding the range computation. Also, simplify the type > declarations for the relevant variables. > > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-kbuild-all/202601240453.QCjgGdJa-lkp@intel.com/ > Fixes: 93552c9a3350 ("mm: folio_zero_user: cache neighbouring pages") > Signed-off-by: Ankur Arora > --- > > Hi Andrew > > As David pointed out, the previous open coded version makes a few > unnecessary changes. Could you queue this one instead? > I'm late, maybe this is already upstream. > Thanks > Ankur > > > mm/memory.c | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index ce933ee4a3dd..f5bfc082ab61 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -7284,7 +7284,7 @@ void folio_zero_user(struct folio *folio, unsigned long addr_hint) > const unsigned long base_addr = ALIGN_DOWN(addr_hint, folio_size(folio)); > const long fault_idx = (addr_hint - base_addr) / PAGE_SIZE; > const struct range pg = DEFINE_RANGE(0, folio_nr_pages(folio) - 1); > - const int radius = FOLIO_ZERO_LOCALITY_RADIUS; > + const long radius = FOLIO_ZERO_LOCALITY_RADIUS; > struct range r[3]; > int i; > > @@ -7292,24 +7292,23 @@ void folio_zero_user(struct folio *folio, unsigned long addr_hint) > * Faulting page and its immediate neighbourhood. Will be cleared at the > * end to keep its cachelines hot. > */ > - r[2] = DEFINE_RANGE(clamp_t(s64, fault_idx - radius, pg.start, pg.end), > - clamp_t(s64, fault_idx + radius, pg.start, pg.end)); > + r[2] = DEFINE_RANGE(fault_idx - radius < (long)pg.start ? pg.start : fault_idx - radius, > + fault_idx + radius > (long)pg.end ? pg.end : fault_idx + radius); > + LGTM, although it could likely be made a bit more readable by using some temporary variables. const long fault_idx_low = fault_idx - radius; const long fault_idx_high = fault_idx + radius; r[2] = DEFINE_RANGE(fault_idx_low < (long)pg.start ? pg.start : fault_idx_low, fault_idx_high > (long)pg.end ? pg.end : fault_idx_high); Well, still a bit unreadable, so ... :) > > /* Region to the left of the fault */ > - r[1] = DEFINE_RANGE(pg.start, > - clamp_t(s64, r[2].start - 1, pg.start - 1, r[2].start)); > + r[1] = DEFINE_RANGE(pg.start, r[2].start - 1); > > /* Region to the right of the fault: always valid for the common fault_idx=0 case. */ > - r[0] = DEFINE_RANGE(clamp_t(s64, r[2].end + 1, r[2].end, pg.end + 1), > - pg.end); > + r[0] = DEFINE_RANGE(r[2].end + 1, pg.end); TBH, without the clamp that looks much more readable here. > > for (i = 0; i < ARRAY_SIZE(r); i++) { > const unsigned long addr = base_addr + r[i].start * PAGE_SIZE; > - const unsigned int nr_pages = range_len(&r[i]); > + const long nr_pages = (long)range_len(&r[i]); > struct page *page = folio_page(folio, r[i].start); > > if (nr_pages > 0) > - clear_contig_highpages(page, addr, nr_pages); > + clear_contig_highpages(page, addr, (unsigned int)nr_pages); Is that cast really required? -- Cheers, David