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 BDFF1556BA2; Tue, 22 Sep 2026 15:39:32 +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=1790091574; cv=none; b=iT7E5dxqMJobxKMyhozLU0/93KbL9lBnVtDaRdSvf0rNJ8Mev1U2acpr/kaukcpNojw9YfJQVqkfEwK+F8+L6kPBnc9OZ6gRMT/eAtTbLQLx+3UEQQCe0/G/xIYSWFvCo3SO4NAP7sXB1GOzIK0Am8Twgz7drJy8mprudFyHHj8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790091574; c=relaxed/simple; bh=vMbfUQkzgTSKIjU6KPYoUnxQRGxa3kcmbXWa6+LkIAs=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ZMSTvRI+Wvq0EABOWoLniUfdrphH2gH4+gEdk1fYAs5xoW9PmIK6LArGGj9ZeL73mLR2acMf8xkuKArwKQxPuHWlUiG/WYwn3OyE7vQjikQsMPW2J8Lwy3Bs0vFI0x5ComX+KKIsvQdyseUIMnflPie/1rG3qCx53WSrtoQtpUw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bm22U7Fi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bm22U7Fi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC2761F00893; Tue, 22 Sep 2026 15:39:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790091572; bh=ZF+xTol/hcpNyDp5nDHTBbzlkakusmjcTTc5URGnJdE=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=bm22U7FiSQN+ggAF3r9V2Q0hTdDX+haEkgL46cvJgXYTzo9vM+dDmqmTp/9VihJx9 SAYWsTV+vy+dbQpZKb9sP8GwOF+y1UmnWNMyeMBUje5FYSeaC4hKYJ5rn1h1QVROYs efwCayHiTBPyeuycqYp1H+zPMa928CepF/CWHc5i6rvbMd6bsdfXEJ/1JT/ma/gslH 9SxWv5o4OHw2VFBuo+ZThwnCN4O+Y0kIv9egppeagC7qOn9OEZjvPf/H2h8AtIeOgN azEjXleHU0E17mzmNlt7cHeEN8qRySe/5AzeXWgm5MV/ZURMFf47PIrjLE+QUEhKvU go/z03ESbnwtw== From: "Lorenzo Stoakes (ARM)" Date: Tue, 22 Sep 2026 16:35:39 +0100 Subject: [PATCH v4 08/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sh-X2 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260922-rcu-pagetable-freeing-v4-8-fe1ad1f1e303@kernel.org> References: <20260922-rcu-pagetable-freeing-v4-0-fe1ad1f1e303@kernel.org> In-Reply-To: <20260922-rcu-pagetable-freeing-v4-0-fe1ad1f1e303@kernel.org> To: Andrew Morton , David Hildenbrand , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Guo Ren , Brian Cain , Geert Uytterhoeven , Dinh Nguyen , Simon Schuster , Jonas Bonn , Stefan Kristiansson , Stafford Horne , Rich Felker , John Paul Adrian Glaubitz , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Russell King , Vineet Gupta , Michal Simek , Chris Zankel , Max Filippov , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , "David S. Miller" , Andreas Larsson , Richard Henderson , Matt Turner , Magnus Lindholm , Catalin Marinas , Mark Rutland , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Madhavan Srinivasan , Michael Ellerman , "Christophe Leroy (CS GROUP)" , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Richard Weinberger , Anton Ivanov , Johannes Berg , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Arnd Bergmann , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , John Hubbard , Peter Xu , Yoshinori Sato , Shakeel Butt , Jonathan Corbet , Randy Dunlap Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-snps-arc@lists.infradead.org, linux-arch@vger.kernel.org, sparclinux@vger.kernel.org, linux-alpha@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, Hugh Dickins , Qi Zheng , linux-doc@vger.kernel.org, "Lorenzo Stoakes (ARM)" X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=4177; i=ljs@kernel.org; h=from:subject:message-id; bh=vMbfUQkzgTSKIjU6KPYoUnxQRGxa3kcmbXWa6+LkIAs=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLI2LchJrVl3zeaaXwmbwql3cltt8pgMlDSuhvuk5AVm7 6w8HqDaUcrCIMbFICumyPL8i/j+IJGweZ0X/N1g5rAygQxh4OIUgIn828LI8CH2f8W8VZv/XLr3 dUp+cWMge9j7g/ffCDZ7Lv2fsPD4iu+MDM+t3WJETxq7bDm//Y1TqcBOTyNBzhqvo3VPjkyVn/d 9Ig8A X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Currently, non-x2 sh specifies CONFIG_MMU_GATHER_RCU_TABLE_FREE allowing RCU page table freeing. sh-X2 is problematic because it utilises slab-allocated PMD page tables, and thus tlb_remove_ptdesc() cannot be used in these cases. All other sh variants are fine as commit e3ecf7c7d082 ("mm: pgtable: convert some architectures to use tlb_remove_ptdesc()") already converted page table freeing to use tlb_remove_ptdesc(), which does so after an RCU grace period when CONFIG_MMU_GATHER_RCU_TABLE_FREE is specified. Resolve this issue by firstly specifying CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE for sh-X2, so the arch can provide its own __tlb_remove_table() implementation (called after the RCU grace period). Then, convert __pmd_free_tlb() to tag the pointer to the PMD, and have __tlb_remove_table() check this tag to determine whether to free via the slab or to use pagetable_dtor_free(). This follows the pattern used by sparc64 as implemented in commit 4a0100f7546f ("sparc64: use RCU page table freeing"). Previously __pmd_free_tlb() freed PMD page tables immediately, before any TLB flush IPI. This seems to be a pre-existing bug, which this change also resolves. CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE is only specified for sh-X2, as setting it disables CONFIG_PT_RECLAIM and causes __tlb_remove_table_one() to call tlb_remove_table_sync_rcu() and synchronize_rcu() in turn, and this is not necessary for other sh variants. This forms part of an overall effort to switch every architecture to this mode. Acked-by: Kiryl Shutsemau (Meta) Signed-off-by: Lorenzo Stoakes (ARM) --- arch/sh/Kconfig | 3 ++- arch/sh/include/asm/pgalloc.h | 6 +++++- arch/sh/mm/pgtable.c | 20 ++++++++++++++++++++ 3 files changed, 27 insertions(+), 2 deletions(-) diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index 204f64912f0e..75236bef6f16 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -33,6 +33,7 @@ config SUPERH select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_KGDB select HAVE_ARCH_SECCOMP_FILTER + select HAVE_ARCH_TLB_REMOVE_TABLE if X2TLB select HAVE_ARCH_TRACEHOOK select HAVE_DEBUG_BUGVERBOSE select HAVE_DEBUG_KMEMLEAK @@ -61,7 +62,7 @@ config SUPERH select HAVE_SYSCALL_TRACEPOINTS select IRQ_FORCED_THREADING select LOCK_MM_AND_FIND_VMA - select MMU_GATHER_RCU_TABLE_FREE if MMU && !X2TLB + select MMU_GATHER_RCU_TABLE_FREE if MMU select MODULES_USE_ELF_RELA select NEED_SG_DMA_LENGTH select NO_DMA if !MMU && !DMA_COHERENT diff --git a/arch/sh/include/asm/pgalloc.h b/arch/sh/include/asm/pgalloc.h index 6fe7123d38fa..67ce7fa23fa1 100644 --- a/arch/sh/include/asm/pgalloc.h +++ b/arch/sh/include/asm/pgalloc.h @@ -17,7 +17,11 @@ extern void pgd_free(struct mm_struct *mm, pgd_t *pgd); extern void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd); extern pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address); extern void pmd_free(struct mm_struct *mm, pmd_t *pmd); -#define __pmd_free_tlb(tlb, pmdp, addr) pmd_free((tlb)->mm, (pmdp)) +extern void __tlb_remove_table(void *table); + +/* PMDs are slab-allocated, tag so they are freed correctly. */ +#define __pmd_free_tlb(tlb, pmdp, addr) \ + tlb_remove_table((tlb), (void *)((unsigned long)(pmdp) | 1)) #endif static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, diff --git a/arch/sh/mm/pgtable.c b/arch/sh/mm/pgtable.c index 3a4085ea0161..f6184b86b89c 100644 --- a/arch/sh/mm/pgtable.c +++ b/arch/sh/mm/pgtable.c @@ -56,4 +56,24 @@ void pmd_free(struct mm_struct *mm, pmd_t *pmd) { kmem_cache_free(pmd_cachep, pmd); } + +static void __tlb_remove_table_slab(void *table) +{ + kmem_cache_free(pmd_cachep, table); +} + +static void __tlb_remove_table_pgtable(void *table) +{ + pagetable_dtor_free(table); +} + +void __tlb_remove_table(void *table) +{ + const unsigned long addr = (unsigned long)table; + + if (addr & 1) + __tlb_remove_table_slab((void *)(addr & ~1UL)); + else + __tlb_remove_table_pgtable(table); +} #endif /* PAGETABLE_LEVELS > 2 */ -- 2.55.0