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 716AF63DA for ; Thu, 5 Jan 2023 12:56:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3F59C433F1; Thu, 5 Jan 2023 12:56:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672923404; bh=JpRoCOycaWZnoJoaIeuyi/UYW4SMCrZhAs7rTvx7/Ng=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ka4L/A7YzwB5ugviM15u1av5f2yLWBLUWRROkoExpf5orcIwKK4h54ZrhK25Hnxon CEtvYkHmTyCbAb6lpUzS4JHmgS4fCp6CY+zfY2UqmBhoXJ9FMGsaE91JsLzrURc+mj fd8FtS80Ops/8Uduv6ZEWQ6oywgVYIw4x3RLiua8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jann Horn , Yang Shi , David Hildenbrand , John Hubbard , Peter Xu , Andrew Morton Subject: [PATCH 4.9 001/251] mm/khugepaged: fix GUP-fast interaction by sending IPI Date: Thu, 5 Jan 2023 13:52:18 +0100 Message-Id: <20230105125334.799380749@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230105125334.727282894@linuxfoundation.org> References: <20230105125334.727282894@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jann Horn commit 2ba99c5e08812494bc57f319fb562f527d9bacd8 upstream. Since commit 70cbc3cc78a99 ("mm: gup: fix the fast GUP race against THP collapse"), the lockless_pages_from_mm() fastpath rechecks the pmd_t to ensure that the page table was not removed by khugepaged in between. However, lockless_pages_from_mm() still requires that the page table is not concurrently freed. Fix it by sending IPIs (if the architecture uses semi-RCU-style page table freeing) before freeing/reusing page tables. Link: https://lkml.kernel.org/r/20221129154730.2274278-2-jannh@google.com Link: https://lkml.kernel.org/r/20221128180252.1684965-2-jannh@google.com Link: https://lkml.kernel.org/r/20221125213714.4115729-2-jannh@google.com Fixes: ba76149f47d8 ("thp: khugepaged") Signed-off-by: Jann Horn Reviewed-by: Yang Shi Acked-by: David Hildenbrand Cc: John Hubbard Cc: Peter Xu Cc: Signed-off-by: Andrew Morton [manual backport: two of the three places in khugepaged that can free ptes were refactored into a common helper between 5.15 and 6.0; TLB flushing was refactored between 5.4 and 5.10; TLB flushing was refactored between 4.19 and 5.4; pmd collapse for PTE-mapped THP was only added in 5.4; ugly hack for s390 in <=4.19 and arm] Signed-off-by: Jann Horn Signed-off-by: Greg Kroah-Hartman --- include/asm-generic/tlb.h | 6 ++++++ mm/khugepaged.c | 15 +++++++++++++++ mm/memory.c | 5 +++++ 3 files changed, 26 insertions(+) --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -60,6 +60,12 @@ struct mmu_table_batch { extern void tlb_table_flush(struct mmu_gather *tlb); extern void tlb_remove_table(struct mmu_gather *tlb, void *table); +void tlb_remove_table_sync_one(void); + +#else + +static inline void tlb_remove_table_sync_one(void) { } + #endif /* --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -20,6 +20,19 @@ #include #include "internal.h" +/* gross hack for <=4.19 stable */ +#if defined(CONFIG_S390) || defined(CONFIG_ARM) +static void tlb_remove_table_smp_sync(void *arg) +{ + /* Simply deliver the interrupt */ +} + +static void tlb_remove_table_sync_one(void) +{ + smp_call_function(tlb_remove_table_smp_sync, NULL, 1); +} +#endif + enum scan_result { SCAN_FAIL, SCAN_SUCCEED, @@ -1044,6 +1057,7 @@ static void collapse_huge_page(struct mm _pmd = pmdp_collapse_flush(vma, address, pmd); spin_unlock(pmd_ptl); mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); + tlb_remove_table_sync_one(); spin_lock(pte_ptl); isolated = __collapse_huge_page_isolate(vma, address, pte); @@ -1293,6 +1307,7 @@ static void retract_page_tables(struct a _pmd = pmdp_collapse_flush(vma, addr, pmd); spin_unlock(ptl); atomic_long_dec(&mm->nr_ptes); + tlb_remove_table_sync_one(); pte_free(mm, pmd_pgtable(_pmd)); } up_write(&mm->mmap_sem); --- a/mm/memory.c +++ b/mm/memory.c @@ -349,6 +349,11 @@ static void tlb_remove_table_smp_sync(vo /* Simply deliver the interrupt */ } +void tlb_remove_table_sync_one(void) +{ + smp_call_function(tlb_remove_table_smp_sync, NULL, 1); +} + static void tlb_remove_table_one(void *table) { /*