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 42565382293 for ; Mon, 18 May 2026 17:54:19 +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=1779126859; cv=none; b=KPUa9nlwVoVu2be+OPw76BI0oZ35CYo5lYhe6/Top2BIlpAbuxKJgJJSdzXINtTukaJAYmugmTBLYFAzdd1OVtE/yQ5bG4igll1GI5s9hRG4VuarOT4HBRX4A1SeX7hPjkOQ9cRdsMIyPiJx6JEoOPxqXX2wneG1lcptFfvftiI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779126859; c=relaxed/simple; bh=mZ99ejMd6rovr1ewQFRxBTT5Cg2IOTm7DB7RlWh4W6s=; h=Date:To:From:Subject:Message-Id; b=YDI6pkD7NXRuus0e2aGntTEv+yqodpDXbjZAJY/JyTUH2a1Vac9Ag+dMzxRYtLcRjrGEp9R8hiaXwGbC2PNWM12wDS5OVx+lLmJoLvwCCarc97sFxCqmcMICS+87xYHat98V7CVqj3MmwZwr6CbZ2has/7GM5uF38NphSWBRcGg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=FyLu2Kqd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="FyLu2Kqd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18977C2BCB7; Mon, 18 May 2026 17:54:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1779126859; bh=mZ99ejMd6rovr1ewQFRxBTT5Cg2IOTm7DB7RlWh4W6s=; h=Date:To:From:Subject:From; b=FyLu2KqdQPu/9g1MbZ+M3X+ycaHl8iMa0QflxXkN001Z8Vq2rKJgExFrUYC5EMNEo PKgTlGM6wv7mNFK43sBZb2QMLga7kXEjJYdwoOzF4W6Xi0LdUfAI30wMTzERktZEXj v+j4CL4+tHVUjf8+Ngq7Gmn3Ha61+5q0ygYkE0Co= Date: Mon, 18 May 2026 10:54:18 -0700 To: mm-commits@vger.kernel.org,joonwonkang@google.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] percpu-do-not-trust-hint-starts-when-they-are-not-set.patch removed from -mm tree Message-Id: <20260518175419.18977C2BCB7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: percpu: do not trust hint starts when they are not set has been removed from the -mm tree. Its filename was percpu-do-not-trust-hint-starts-when-they-are-not-set.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: Joonwon Kang Subject: percpu: do not trust hint starts when they are not set Date: Sun, 10 May 2026 07:21:47 +0000 contig_hint_start can be trusted outside the hint update function since it will be updated everytime contig_hint is broken. On the other hand, scan_hint_start might still be invalid anywhere in the code due to the broken scan_hint not being updated promptly. If those starts are trusted when they are not set, it could lead to false invalidation or update of the hints. Link: https://lore.kernel.org/20260510072149.1279887-2-joonwonkang@google.com Signed-off-by: Joonwon Kang Cc: Christoph Lameter Cc: Dennis Zhou Cc: Tejun Heo Cc: Signed-off-by: Andrew Morton --- mm/percpu.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) --- a/mm/percpu.c~percpu-do-not-trust-hint-starts-when-they-are-not-set +++ a/mm/percpu.c @@ -640,12 +640,13 @@ static void pcpu_block_update(struct pcp if (contig > block->contig_hint) { /* promote the old contig_hint to be the new scan_hint */ - if (start > block->contig_hint_start) { + if (block->contig_hint && start > block->contig_hint_start) { if (block->contig_hint > block->scan_hint) { block->scan_hint_start = block->contig_hint_start; block->scan_hint = block->contig_hint; - } else if (start < block->scan_hint_start) { + } else if (block->scan_hint && + start < block->scan_hint_start) { /* * The old contig_hint == scan_hint. But, the * new contig is larger so hold the invariant @@ -664,10 +665,12 @@ static void pcpu_block_update(struct pcp __ffs(start) > __ffs(block->contig_hint_start))) { /* start has a better alignment so use it */ block->contig_hint_start = start; - if (start < block->scan_hint_start && + if (block->scan_hint && + start < block->scan_hint_start && block->contig_hint > block->scan_hint) block->scan_hint = 0; - } else if (start > block->scan_hint_start || + } else if ((block->scan_hint && + start > block->scan_hint_start) || block->contig_hint > block->scan_hint) { /* * Knowing contig == contig_hint, update the scan_hint @@ -845,7 +848,8 @@ static void pcpu_block_update_hint_alloc PCPU_BITMAP_BLOCK_BITS, s_off + bits); - if (pcpu_region_overlap(s_block->scan_hint_start, + if (s_block->scan_hint && + pcpu_region_overlap(s_block->scan_hint_start, s_block->scan_hint_start + s_block->scan_hint, s_off, s_off + bits)) @@ -889,7 +893,8 @@ static void pcpu_block_update_hint_alloc /* reset the block */ e_block++; } else { - if (e_off > e_block->scan_hint_start) + if (e_block->scan_hint && + e_off > e_block->scan_hint_start) e_block->scan_hint = 0; e_block->left_free = 0; @@ -922,7 +927,8 @@ static void pcpu_block_update_hint_alloc if (nr_empty_pages) pcpu_update_empty_pages(chunk, -nr_empty_pages); - if (pcpu_region_overlap(chunk_md->scan_hint_start, + if (chunk_md->scan_hint && + pcpu_region_overlap(chunk_md->scan_hint_start, chunk_md->scan_hint_start + chunk_md->scan_hint, bit_off, _ Patches currently in -mm which might be from joonwonkang@google.com are a.patch percpu-introduce-struct-pcpu_region.patch percpu-fix-hint-invariant-breakage.patch