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 DA1313603E8 for ; Sun, 5 Jul 2026 07:32:01 +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=1783236723; cv=none; b=Ho0wu2CgD+DlTXRLW/AmQ3x8DyrUcj7UV/7C0LRmhCDRtVr3BllbqndmD9stLG8z0pqwISTJ4Dp8ibChqfPvULjpxH9I87sLYz4v3fOWbwKCXkwn9rI8OCl1Qu+hntdSNPzZBx8MDb1dCuY3KOBIRd3kB2Nyx+TEi5VR7Lbvdn8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783236723; c=relaxed/simple; bh=2h9SZDjbWYiOQDHH7df+1ZLhlF3pI1OHK6n2Lb9eo0E=; h=Date:To:From:Subject:Message-Id; b=cTs/js1xxr37XlTVdhRy/QuWY0jnYYPdGfdauT0Um44q9aQHXkwqttFPBjUQZvpkBCgELsJqXjefxL6IZri01HU4038tleZuzedZv5hD3KhScaXiuGxDwSxlnFYtkTaqcQkfCp6+wK+R4R2MrAiK2RYcDi0qGoJbhcf25BCTBQU= 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=AGDvYffJ; 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="AGDvYffJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACB291F000E9; Sun, 5 Jul 2026 07:32:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783236721; bh=87yPhfAKlgZ/1L36iYJ498N2fmPQloYuB9VmC3wjWJE=; h=Date:To:From:Subject; b=AGDvYffJp+Wmc0Q51Rb/2KIpwvK5hQZcZ7vsUH3M49UsDm2Qb62V6sM++fS6mFQcA dbY/JZ+10CWk/FRqoy6Ct4YK4h4gr95Ig/BS7FQgMgusB69Muxo79ZMPEYu0zQnh+/ rGyM8CmvtzvON9uAbOmGDzSXJqCWE94xEsXjmYhk= Date: Sun, 05 Jul 2026 00:32:01 -0700 To: mm-commits@vger.kernel.org,jackmanb@google.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-factor-out-can_spin_trylock.patch added to mm-new branch Message-Id: <20260705073201.ACB291F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: factor out can_spin_trylock() has been added to the -mm mm-new branch. Its filename is mm-factor-out-can_spin_trylock.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-factor-out-can_spin_trylock.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Brendan Jackman Subject: mm: factor out can_spin_trylock() Date: Fri, 03 Jul 2026 12:31:58 +0000 Deduplicate checks for whether the current context is safe for spin_trylock(). Does this function really belong in mm/internal.h or is it generic? Not sure. If someone ends up duplicating this logic elsewhere in the kernel, that would be a shame. But if it goes in some generic header, someone treats it as documentation about where it's guaranteed safe to spin_trylock(), and then it emerges that there are other subtle preconditions that didn't affect the mm usecase, that would be worse. So, just be conservative and keep it local. Link: https://lore.kernel.org/20260703-alloc-trylock-v5-18-c87b714e19d3@google.com Signed-off-by: Brendan Jackman Suggested-by: Harry Yoo Link: https://lore.kernel.org/all/397859cb-b127-4cc6-9c71-044afc99bf0c@kernel.org/ Reviewed-by: Vlastimil Babka (SUSE) Reviewed-by: Harry Yoo (Oracle) Reviewed-by: Zi Yan Signed-off-by: Andrew Morton --- mm/internal.h | 23 +++++++++++++++++++++++ mm/page_alloc.c | 17 +---------------- mm/slub.c | 10 +--------- 3 files changed, 25 insertions(+), 25 deletions(-) --- a/mm/internal.h~mm-factor-out-can_spin_trylock +++ a/mm/internal.h @@ -1716,4 +1716,27 @@ static inline void mm_prepare_for_swap_e } } +static inline bool can_spin_trylock(void) +{ + /* + * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is + * unsafe in NMI. If spin_trylock() is called from hard IRQ the current + * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will + * mark the task as the owner of another rt_spin_lock which will + * confuse PI logic, so return immediately if called from hard IRQ or + * NMI. + * + * Note, irqs_disabled() case is ok. spin_trylock() can be called + * from raw_spin_lock_irqsave region. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) + return false; + + /* On UP, spin_trylock() always succeeds even when it is locked */ + if (!IS_ENABLED(CONFIG_SMP) && in_nmi()) + return false; + + return true; +} + #endif /* __MM_INTERNAL_H */ --- a/mm/page_alloc.c~mm-factor-out-can_spin_trylock +++ a/mm/page_alloc.c @@ -5291,22 +5291,7 @@ static inline bool alloc_order_allowed(g static inline bool alloc_nolock_allowed(void) { - /* - * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is - * unsafe in NMI. If spin_trylock() is called from hard IRQ the current - * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will - * mark the task as the owner of another rt_spin_lock which will - * confuse PI logic, so return immediately if called from hard IRQ or - * NMI. - * - * Note, irqs_disabled() case is ok. This function can be called - * from raw_spin_lock_irqsave region. - */ - if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) - return false; - - /* On UP, spin_trylock() always succeeds even when it is locked */ - if (!IS_ENABLED(CONFIG_SMP) && in_nmi()) + if (!can_spin_trylock()) return false; /* Bailout, since _deferred_grow_zone() needs to take a lock */ --- a/mm/slub.c~mm-factor-out-can_spin_trylock +++ a/mm/slub.c @@ -5408,15 +5408,7 @@ static void *__kmalloc_nolock_noprof(DEC if (unlikely(!size)) return ZERO_SIZE_PTR; - /* - * See the comment for the same check in - * alloc_frozen_pages_nolock_noprof() - */ - if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) - return NULL; - - /* On UP, spin_trylock() always succeeds even when it is locked */ - if (!IS_ENABLED(CONFIG_SMP) && in_nmi()) + if (!can_spin_trylock()) return NULL; retry: _ Patches currently in -mm which might be from jackmanb@google.com are mm-page_alloc-drop-flag-conversion-optimisation.patch mm-secretmem-disable-under-highmem.patch mm-page_alloc-rename-alloc_trylock-alloc_nolock.patch mm-page_alloc-some-renames-to-clarify-alloc_flags-scopes.patch mm-name-some-args-in-a-function-declaration.patch mm-split-out-internal-page_alloch.patch mm-page_alloc-unify-__alloc_frozen_pages_noprof.patch mm-page_alloc-relax-gfp-warn-in-nolock-allocs.patch mm-move-some-stuff-to-mm-page_alloch.patch perf-x86-intel-use-higher-level-allocator-api.patch kvm-vmx-use-higher-level-allocator-api.patch x86-virt-use-higher-level-allocator-api.patch sgi-xp-use-higher-level-allocator-api.patch net-funeth-switch-to-higher-level-allocator-api.patch mm-remove-__alloc_pages_node.patch mm-move-__alloc_pages-to-mm-page_alloch.patch mm-replace-__gfp_no_codetag-with-alloc_no_codetag.patch mm-page_alloc-drop-alloc_flags-arg-from-alloc_flags_cma.patch mm-factor-out-can_spin_trylock.patch