From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8A16638B127 for ; Fri, 29 May 2026 04:51:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780030303; cv=none; b=K5rAFZwZKejT7JBrV0d3jxEGbqSTyKbS/ef6+1WDZgED1aUD0Qc78UAQLxAEq/gatxbaW4PIMgUtmKbSOb7nx4BXHhgilhDFWxuqb4FLkz06hM0Y7OyqxUYHZ1vxJSCD46qosx9tqfGZcpWniaNF51Yi0eNGrbJrU6N9wdvPopM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780030303; c=relaxed/simple; bh=gQKPxbFTZ1Zx6oCsqJgj+/X9tZYW5vDTQnE9Tc4VYUY=; h=Date:To:From:Subject:Message-Id; b=BNWeCRsa+aDlUGKXrmgHgd0nKXgd+Ao1xYm5mkVLLgveQHyyjBmqC52xyga0+UCjrNQlZzSHnNWF2kLDcDZWi79JmDLlSGvpy/Iw3Gqq6hRr5EV/JIhoA4ouJ/nVwHqMgL1e9gAQss3XinavOj0KkZOYcXI8lru1s6KF6OTX4tU= 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=ssyKER3H; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="ssyKER3H" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 455191F00893; Fri, 29 May 2026 04:51:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1780030302; bh=H1LghdE+JeGm+9Pdx7t0/yUOMK6cNhYrTjS2/thMUVI=; h=Date:To:From:Subject; b=ssyKER3HQymaIrwk1SvBd5hiK6vOHTR/QzSTYDSs/2vbZ/5rLsdMBJUM9CLQnaDye Xk/b5E902OAuqWF3MMk/yWK+YQ9TSaMVrq+J/PZWf7nLPCn1jFmV9oOZfyMLpuPHnN 4tbqyZ4p7G0N1zfSL6Db+H/UzFxr+LvJA/2ARk54= Date: Thu, 28 May 2026 21:51:41 -0700 To: mm-commits@vger.kernel.org,tj@kernel.org,dennis@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: <20260529045142.455191F00893@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: Wed, 13 May 2026 08:51:14 +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/20260513085117.1024175-2-joonwonkang@google.com Signed-off-by: Joonwon Kang Reviewed-by: Dennis Zhou Cc: Tejun Heo 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 percpu-introduce-struct-pcpu_region.patch percpu-fix-hint-invariant-breakage.patch