From patchwork Wed Oct 19 17:08:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Luck X-Patchwork-Id: 1692116 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=eoFAVHGf; dkim-atps=neutral Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384) server-digest SHA384) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4MsxzW0H7Hz23k2 for ; Thu, 20 Oct 2022 04:09:27 +1100 (AEDT) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4MsxzN6vVLz3c4S for ; Thu, 20 Oct 2022 04:09:20 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=eoFAVHGf; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=intel.com (client-ip=134.134.136.24; helo=mga09.intel.com; envelope-from=tony.luck@intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=eoFAVHGf; dkim-atps=neutral Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Msxz10c31z3bl0 for ; Thu, 20 Oct 2022 04:08:55 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1666199341; x=1697735341; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Zm5MM+MQE2zvO00SCaUTpTsivTJ9TberyUbpMfFKGfw=; b=eoFAVHGfEl7kP4NavmJxNVKsr+3rOVmMM3xpp1/kk5xrDaLrAF94m1Z1 g2LpoVcl7ETExbscwg2ABSaGoz3AfJu+dAfA6R5tWU38tzKiHJpIrnuCu fiPiCDVLpz7DCJPCOANqjGpQfbSE7Z+wgOiLToBF02o3jVzJ9bOPiDQhl hw5kiEnHkiHY9d2AJt42AKgNlbkS0MAiB9ef3rtTLt1pTANuDgqC+sp6W yzCn57huYpF+kVMKl3Ne6bBstpmIMbGLEV3cCLS4o7ahjYmX8s9CVumyy fG3NqL6L0bQEK8WU2CMeg0Cg9k7iGr3JNJuC65pj6Aj3XX+44GX4sG9jb Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10505"; a="307581304" X-IronPort-AV: E=Sophos;i="5.95,196,1661842800"; d="scan'208";a="307581304" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2022 10:08:43 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10505"; a="692489392" X-IronPort-AV: E=Sophos;i="5.95,196,1661842800"; d="scan'208";a="692489392" Received: from agluck-desk3.sc.intel.com ([172.25.222.78]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2022 10:08:43 -0700 From: Tony Luck To: Naoya Horiguchi , Andrew Morton Subject: [PATCH v2] mm, hwpoison: Try to recover from copy-on write faults Date: Wed, 19 Oct 2022 10:08:35 -0700 Message-Id: <20221019170835.155381-1-tony.luck@intel.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: References: MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Miaohe Lin , Matthew Wilcox , linux-kernel@vger.kernel.org, Nicholas Piggin , linux-mm@kvack.org, Tony Luck , Shuai Xue , Dan Williams , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" If the kernel is copying a page as the result of a copy-on-write fault and runs into an uncorrectable error, Linux will crash because it does not have recovery code for this case where poison is consumed by the kernel. It is easy to set up a test case. Just inject an error into a private page, fork(2), and have the child process write to the page. I wrapped that neatly into a test at: git://git.kernel.org/pub/scm/linux/kernel/git/aegl/ras-tools.git just enable ACPI error injection and run: # ./einj_mem-uc -f copy-on-write Add a new copy_user_highpage_mc() function that uses copy_mc_to_kernel() on architectures where that is available (currently x86 and powerpc). When an error is detected during the page copy, return VM_FAULT_HWPOISON to caller of wp_page_copy(). This propagates up the call stack. Both x86 and powerpc have code in their fault handler to deal with this code by sending a SIGBUS to the application. Note that this patch avoids a system crash and signals the process that triggered the copy-on-write action. It does not take any action for the memory error that is still in the shared page. To handle that a call to memory_failure() is needed. But this cannot be done from wp_page_copy() because it holds mmap_lock(). Perhaps the architecture fault handlers can deal with this loose end in a subsequent patch? On Intel/x86 this loose end will often be handled automatically because the memory controller provides an additional notification of the h/w poison in memory, the handler for this will call memory_failure(). This isn't a 100% solution. If there are multiple errors, not all may be logged in this way. Signed-off-by: Tony Luck Reviewed-by: Dan Williams Signed-off-by: Tony Luck --- Changes in V2: Naoya Horiguchi: 1) Use -EHWPOISON error code instead of minus one. 2) Poison path needs also to deal with old_page Tony Luck: Rewrote commit message Added some powerpc folks to Cc: list --- include/linux/highmem.h | 19 +++++++++++++++++++ mm/memory.c | 28 +++++++++++++++++++--------- 2 files changed, 38 insertions(+), 9 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index e9912da5441b..5967541fbf0e 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -319,6 +319,25 @@ static inline void copy_user_highpage(struct page *to, struct page *from, #endif +static inline int copy_user_highpage_mc(struct page *to, struct page *from, + unsigned long vaddr, struct vm_area_struct *vma) +{ + unsigned long ret = 0; +#ifdef copy_mc_to_kernel + char *vfrom, *vto; + + vfrom = kmap_local_page(from); + vto = kmap_local_page(to); + ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE); + kunmap_local(vto); + kunmap_local(vfrom); +#else + copy_user_highpage(to, from, vaddr, vma); +#endif + + return ret; +} + #ifndef __HAVE_ARCH_COPY_HIGHPAGE static inline void copy_highpage(struct page *to, struct page *from) diff --git a/mm/memory.c b/mm/memory.c index f88c351aecd4..a32556c9b689 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2848,8 +2848,14 @@ static inline int pte_unmap_same(struct vm_fault *vmf) return same; } -static inline bool __wp_page_copy_user(struct page *dst, struct page *src, - struct vm_fault *vmf) +/* + * Return: + * -EHWPOISON: copy failed due to hwpoison in source page + * 0: copied failed (some other reason) + * 1: copied succeeded + */ +static inline int __wp_page_copy_user(struct page *dst, struct page *src, + struct vm_fault *vmf) { bool ret; void *kaddr; @@ -2860,8 +2866,9 @@ static inline bool __wp_page_copy_user(struct page *dst, struct page *src, unsigned long addr = vmf->address; if (likely(src)) { - copy_user_highpage(dst, src, addr, vma); - return true; + if (copy_user_highpage_mc(dst, src, addr, vma)) + return -EHWPOISON; + return 1; } /* @@ -2888,7 +2895,7 @@ static inline bool __wp_page_copy_user(struct page *dst, struct page *src, * and update local tlb only */ update_mmu_tlb(vma, addr, vmf->pte); - ret = false; + ret = 0; goto pte_unlock; } @@ -2913,7 +2920,7 @@ static inline bool __wp_page_copy_user(struct page *dst, struct page *src, if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) { /* The PTE changed under us, update local tlb */ update_mmu_tlb(vma, addr, vmf->pte); - ret = false; + ret = 0; goto pte_unlock; } @@ -2932,7 +2939,7 @@ static inline bool __wp_page_copy_user(struct page *dst, struct page *src, } } - ret = true; + ret = 1; pte_unlock: if (locked) @@ -3104,6 +3111,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) pte_t entry; int page_copied = 0; struct mmu_notifier_range range; + int ret; delayacct_wpcopy_start(); @@ -3121,19 +3129,21 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) if (!new_page) goto oom; - if (!__wp_page_copy_user(new_page, old_page, vmf)) { + ret = __wp_page_copy_user(new_page, old_page, vmf); + if (ret <= 0) { /* * COW failed, if the fault was solved by other, * it's fine. If not, userspace would re-fault on * the same address and we will handle the fault * from the second attempt. + * The -EHWPOISON case will not be retried. */ put_page(new_page); if (old_page) put_page(old_page); delayacct_wpcopy_end(); - return 0; + return ret == -EHWPOISON ? VM_FAULT_HWPOISON : 0; } kmsan_copy_page_meta(new_page, old_page); }