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 9B0EE365A0B for ; Tue, 24 Mar 2026 21:44:29 +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=1774388669; cv=none; b=ZF8YEAjrQLEH12ws6y7VSgT3zxh9By96o5bv4NybnnjkhBYH5vxESXIepBOCy7vvVjdLVc1c3OBFA51ykjVlQX53oTHxDnxo8jSSL31K5CPSXttShs7/CzNfB8DSMlqpWPe4vI8Am871ht7KkPbkDQj9q9Dzeqo/XkBSGf66+7c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774388669; c=relaxed/simple; bh=qYbaMqDwVc04e4UZI7t8TM1NpaULDi3Qnjv8knXN8GY=; h=Date:To:From:Subject:Message-Id; b=hrKNnI0WAPokkrYaRsYOQqbFg6zbFwik6Gz1Rsbtqy9bKOrpO7M8cl/LF6F+VEe5/OYFsE/ig1XvOdd1pBPfJqdWK4rAst5Tvew9Tc+4x1kIbKWRn4o7x55/u2unPv7/J3Ysxh9adxgTyAr55YQYVpzXJMD9J+JIhBfhcGjuJtY= 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=WpXy5URW; 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="WpXy5URW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72309C2BC9E; Tue, 24 Mar 2026 21:44:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1774388669; bh=qYbaMqDwVc04e4UZI7t8TM1NpaULDi3Qnjv8knXN8GY=; h=Date:To:From:Subject:From; b=WpXy5URWhMwhvD9AtpUi+pKSDsYt5MBpvz+AajBeS8G9/ruJjDLE7Lsz6+aikPZNi npqDxkY3VgtbehGAMAWqosAxF+oQNUaDUDF00aInL0yS4MNvreAFPrUXFnB7nrPWPN lJxR6l7aSZaTNKSxlcFflgF/dp0i5GH7+PesAq80= Date: Tue, 24 Mar 2026 14:44:28 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,willy@infradead.org,surenb@google.com,rostedt@goodmis.org,mhocko@suse.com,mgorman@techsingularity.net,jackmanb@google.com,hannes@cmpxchg.org,david@kernel.org,bigeasy@linutronix.de,vbabka@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-page_alloc-remove-irq-saving-restoring-from-pcp-locking.patch removed from -mm tree Message-Id: <20260324214429.72309C2BC9E@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/page_alloc: remove IRQ saving/restoring from pcp locking has been removed from the -mm tree. Its filename was mm-page_alloc-remove-irq-saving-restoring-from-pcp-locking.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Vlastimil Babka Subject: mm/page_alloc: remove IRQ saving/restoring from pcp locking Date: Fri, 27 Feb 2026 18:07:59 +0100 Effectively revert commit 038a102535eb ("mm/page_alloc: prevent pcp corruption with SMP=n"). The original problem is now avoided by pcp_spin_trylock() always failing on CONFIG_SMP=n, so we do not need to disable IRQs anymore. It's not a complete revert, because keeping the pcp_spin_(un)lock() wrappers is useful. Rename them from _maybe_irqsave/restore to _nopin. The difference from pcp_spin_trylock()/pcp_spin_unlock() is that the _nopin variants don't perform pcpu_task_pin/unpin(). Link: https://lkml.kernel.org/r/20260227-b4-pcp-locking-cleanup-v1-2-f7e22e603447@kernel.org Signed-off-by: Vlastimil Babka (SUSE) Acked-by: Johannes Weiner Cc: Brendan Jackman Cc: David Hildenbrand (Arm) Cc: Matthew Wilcox (Oracle) Cc: Mel Gorman Cc: Michal Hocko Cc: Sebastian Andrzej Siewior Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/page_alloc.c | 46 ++++++++++++++++------------------------------ 1 file changed, 16 insertions(+), 30 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-remove-irq-saving-restoring-from-pcp-locking +++ a/mm/page_alloc.c @@ -154,24 +154,14 @@ static DEFINE_MUTEX(pcp_batch_high_lock) BUG_ON(1) #endif -#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) -static inline void __flags_noop(unsigned long *flags) { } -#define pcp_spin_lock_maybe_irqsave(ptr, flags) \ -({ \ - __flags_noop(&(flags)); \ - spin_lock(&(ptr)->lock); \ -}) -#define pcp_spin_unlock_maybe_irqrestore(ptr, flags) \ -({ \ - spin_unlock(&(ptr)->lock); \ - __flags_noop(&(flags)); \ -}) -#else -#define pcp_spin_lock_maybe_irqsave(ptr, flags) \ - spin_lock_irqsave(&(ptr)->lock, flags) -#define pcp_spin_unlock_maybe_irqrestore(ptr, flags) \ - spin_unlock_irqrestore(&(ptr)->lock, flags) -#endif +/* + * In some cases we do not need to pin the task to the CPU because we are + * already given a specific cpu's pcp pointer. + */ +#define pcp_spin_lock_nopin(ptr) \ + spin_lock(&(ptr)->lock) +#define pcp_spin_unlock_nopin(ptr) \ + spin_unlock(&(ptr)->lock) #ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID DEFINE_PER_CPU(int, numa_node); @@ -2568,7 +2558,6 @@ static int rmqueue_bulk(struct zone *zon bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp) { int high_min, to_drain, to_drain_batched, batch; - unsigned long UP_flags; bool todo = false; high_min = READ_ONCE(pcp->high_min); @@ -2588,9 +2577,9 @@ bool decay_pcp_high(struct zone *zone, s to_drain = pcp->count - pcp->high; while (to_drain > 0) { to_drain_batched = min(to_drain, batch); - pcp_spin_lock_maybe_irqsave(pcp, UP_flags); + pcp_spin_lock_nopin(pcp); free_pcppages_bulk(zone, to_drain_batched, pcp, 0); - pcp_spin_unlock_maybe_irqrestore(pcp, UP_flags); + pcp_spin_unlock_nopin(pcp); todo = true; to_drain -= to_drain_batched; @@ -2607,15 +2596,14 @@ bool decay_pcp_high(struct zone *zone, s */ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp) { - unsigned long UP_flags; int to_drain, batch; batch = READ_ONCE(pcp->batch); to_drain = min(pcp->count, batch); if (to_drain > 0) { - pcp_spin_lock_maybe_irqsave(pcp, UP_flags); + pcp_spin_lock_nopin(pcp); free_pcppages_bulk(zone, to_drain, pcp, 0); - pcp_spin_unlock_maybe_irqrestore(pcp, UP_flags); + pcp_spin_unlock_nopin(pcp); } } #endif @@ -2626,11 +2614,10 @@ void drain_zone_pages(struct zone *zone, static void drain_pages_zone(unsigned int cpu, struct zone *zone) { struct per_cpu_pages *pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu); - unsigned long UP_flags; int count; do { - pcp_spin_lock_maybe_irqsave(pcp, UP_flags); + pcp_spin_lock_nopin(pcp); count = pcp->count; if (count) { int to_drain = min(count, @@ -2639,7 +2626,7 @@ static void drain_pages_zone(unsigned in free_pcppages_bulk(zone, to_drain, pcp, 0); count -= to_drain; } - pcp_spin_unlock_maybe_irqrestore(pcp, UP_flags); + pcp_spin_unlock_nopin(pcp); } while (count); } @@ -6123,7 +6110,6 @@ static void zone_pcp_update_cacheinfo(st { struct per_cpu_pages *pcp; struct cpu_cacheinfo *cci; - unsigned long UP_flags; pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu); cci = get_cpu_cacheinfo(cpu); @@ -6134,12 +6120,12 @@ static void zone_pcp_update_cacheinfo(st * This can reduce zone lock contention without hurting * cache-hot pages sharing. */ - pcp_spin_lock_maybe_irqsave(pcp, UP_flags); + pcp_spin_lock_nopin(pcp); if ((cci->per_cpu_data_slice_size >> PAGE_SHIFT) > 3 * pcp->batch) pcp->flags |= PCPF_FREE_HIGH_BATCH; else pcp->flags &= ~PCPF_FREE_HIGH_BATCH; - pcp_spin_unlock_maybe_irqrestore(pcp, UP_flags); + pcp_spin_unlock_nopin(pcp); } void setup_pcp_cacheinfo(unsigned int cpu) _ Patches currently in -mm which might be from vbabka@kernel.org are maintainers-add-mm-related-procfs-files-to-mm-sections.patch