From patchwork Fri Oct 21 20:01:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Luck X-Patchwork-Id: 1693253 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=UDPB3Buz; 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)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4MvFkf38r0z23kG for ; Sat, 22 Oct 2022 07:02:49 +1100 (AEDT) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4MvFkc6K8Dz3dwL for ; Sat, 22 Oct 2022 07:02:48 +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=UDPB3Buz; 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=192.55.52.151; helo=mga17.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=UDPB3Buz; dkim-atps=neutral Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) (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 4MvFjF45rcz3045 for ; Sat, 22 Oct 2022 07:01:37 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1666382497; x=1697918497; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=KaF9e0WVFrqnnol9CO30O+x7LQt9U5cOhvA5BN7/yRs=; b=UDPB3Buz7pUllMybyJV8Z9dVh+BD4Ap/d9gE0EOhIWfPwZCyvwkgHAb/ L438HLcx5bH6H9iJNFsLF8QMKfrMrfmz9y1ZcKh9lVWjix3YyrP9JNugg Di2+bnOM7M8JogMLgh4UJ9gliqU9qMhYcAQWi4392dFY9uFn9ZSulWz6x wmNgNvxbdRVid69cFUXfnN6eJO+fb7kkG4fsLMEXWuTm0DmcP0dMJOgrC xbAGKLfhfhU/+UnIvFLSMqXa323/qqjRV90TA8JneciX6hjxsxeMGfhe5 I27YocqD5S0cJmSay8hMieZeTlBY0W9rovs8emRKKh2GGkSwOtbzQr4IH w==; X-IronPort-AV: E=McAfee;i="6500,9779,10507"; a="287493359" X-IronPort-AV: E=Sophos;i="5.95,203,1661842800"; d="scan'208";a="287493359" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Oct 2022 13:01:27 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10507"; a="633069088" X-IronPort-AV: E=Sophos;i="5.95,203,1661842800"; d="scan'208";a="633069088" Received: from agluck-desk3.sc.intel.com ([172.25.222.78]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Oct 2022 13:01:27 -0700 From: Tony Luck To: Naoya Horiguchi , Andrew Morton Subject: [PATCH v3 1/2] mm, hwpoison: Try to recover from copy-on write faults Date: Fri, 21 Oct 2022 13:01:19 -0700 Message-Id: <20221021200120.175753-2-tony.luck@intel.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221021200120.175753-1-tony.luck@intel.com> References: <20221019170835.155381-1-tony.luck@intel.com> <20221021200120.175753-1-tony.luck@intel.com> 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. Reviewed-by: Dan Williams Signed-off-by: Tony Luck Reviewed-by: Naoya Horiguchi Reviewed-by: Miaohe Lin Reviewed-by: Alexander Potapenko --- Changes in V3: Dan Williams Rename copy_user_highpage_mc() to copy_mc_user_highpage() for consistency with Linus' discussion on names of functions that check for machine check. Write complete functions for the have/have-not copy_mc_to_kernel cases (so grep shows there are two versions) Change __wp_page_copy_user() to return 0 for success, negative for fail [I picked -EAGAIN for both non-EHWPOISON cases] 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 | 24 ++++++++++++++++++++++++ mm/memory.c | 30 ++++++++++++++++++++---------- 2 files changed, 44 insertions(+), 10 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index e9912da5441b..a32c64681f03 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -319,6 +319,30 @@ static inline void copy_user_highpage(struct page *to, struct page *from, #endif +#ifdef copy_mc_to_kernel +static inline int copy_mc_user_highpage(struct page *to, struct page *from, + unsigned long vaddr, struct vm_area_struct *vma) +{ + unsigned long ret; + 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); + + return ret; +} +#else +static inline int copy_mc_user_highpage(struct page *to, struct page *from, + unsigned long vaddr, struct vm_area_struct *vma) +{ + copy_user_highpage(to, from, vaddr, vma); + return 0; +} +#endif + #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..b6056eef2f72 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2848,10 +2848,16 @@ 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: + * 0: copied succeeded + * -EHWPOISON: copy failed due to hwpoison in source page + * -EAGAIN: copied failed (some other reason) + */ +static inline int __wp_page_copy_user(struct page *dst, struct page *src, + struct vm_fault *vmf) { - bool ret; + int ret; void *kaddr; void __user *uaddr; bool locked = false; @@ -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_mc_user_highpage(dst, src, addr, vma)) + return -EHWPOISON; + return 0; } /* @@ -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 = -EAGAIN; 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 = -EAGAIN; goto pte_unlock; } @@ -2932,7 +2939,7 @@ static inline bool __wp_page_copy_user(struct page *dst, struct page *src, } } - ret = true; + ret = 0; 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) { /* * 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); }