From patchwork Thu Apr 13 04:13:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kefeng Wang X-Patchwork-Id: 13209742 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3564EC77B6C for ; Thu, 13 Apr 2023 03:55:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229622AbjDMDzO (ORCPT ); Wed, 12 Apr 2023 23:55:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229484AbjDMDzM (ORCPT ); Wed, 12 Apr 2023 23:55:12 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 487C84EE8; Wed, 12 Apr 2023 20:55:09 -0700 (PDT) Received: from dggpemm500001.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Pxm070TYNzrZm9; Thu, 13 Apr 2023 11:53:43 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Thu, 13 Apr 2023 11:55:06 +0800 From: Kefeng Wang To: Naoya Horiguchi , Alexander Viro , Christian Brauner , , , Andrew Morton CC: Miaohe Lin , , , Kefeng Wang Subject: [PATCH] mm: hwpoison: coredump: support recovery from dump_user_range() Date: Thu, 13 Apr 2023 12:13:36 +0800 Message-ID: <20230413041336.26874-1-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.35.3 MIME-Version: 1.0 X-Originating-IP: [10.175.113.25] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The dump_user_range() is used to copy the user page to a coredump file, but if a hardware memory error occurred during copy, which called from __kernel_write_iter() in dump_user_range(), it crashs, CPU: 112 PID: 7014 Comm: mca-recover Not tainted 6.3.0-rc2 #425 pc : __memcpy+0x110/0x260 lr : _copy_from_iter+0x3bc/0x4c8 ... Call trace: __memcpy+0x110/0x260 copy_page_from_iter+0xcc/0x130 pipe_write+0x164/0x6d8 __kernel_write_iter+0x9c/0x210 dump_user_range+0xc8/0x1d8 elf_core_dump+0x308/0x368 do_coredump+0x2e8/0xa40 get_signal+0x59c/0x788 do_signal+0x118/0x1f8 do_notify_resume+0xf0/0x280 el0_da+0x130/0x138 el0t_64_sync_handler+0x68/0xc0 el0t_64_sync+0x188/0x190 Generally, the '->write_iter' of file ops will use copy_page_from_iter() and copy_page_from_iter_atomic(), change memcpy() to copy_mc_to_kernel() in both of them to handle #MC during source read, which stop coredump processing and kill the task instead of kernel panic, but the source address may not always an user address, so introduce a new copy_mc flag in struct iov_iter{} to indicate that the iter could do a safe memory copy, also introduce the helpers to set/clear/check the flag, for now, it's only used in coredump's dump_user_range(), but it could expand to any other scenarios to fix the similar issue. Signed-off-by: Kefeng Wang --- fs/coredump.c | 2 ++ include/linux/uio.h | 26 ++++++++++++++++++++++++++ lib/iov_iter.c | 17 +++++++++++++++-- 3 files changed, 43 insertions(+), 2 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 5df1e6e1eb2b..d1c82ec86797 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -882,7 +882,9 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) pos = file->f_pos; bvec_set_page(&bvec, page, PAGE_SIZE, 0); iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE); + iov_iter_set_copy_mc(&iter); n = __kernel_write_iter(cprm->file, &iter, &pos); + iov_iter_clear_copy_mc(&iter); if (n != PAGE_SIZE) return 0; file->f_pos = pos; diff --git a/include/linux/uio.h b/include/linux/uio.h index c459e1d5772b..4a549ce2f6d9 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -43,6 +43,7 @@ struct iov_iter { bool nofault; bool data_source; bool user_backed; + bool copy_mc; size_t iov_offset; /* * Hack alert: overlay ubuf_iovec with iovec + count, so @@ -142,6 +143,30 @@ static inline bool user_backed_iter(const struct iov_iter *i) return i->user_backed; } +#ifdef CONFIG_ARCH_HAS_COPY_MC +static inline void iov_iter_set_copy_mc(struct iov_iter *i) +{ + i->copy_mc = true; +} + +static inline void iov_iter_clear_copy_mc(struct iov_iter *i) +{ + i->copy_mc = false; +} + +static inline bool iov_iter_is_copy_mc(const struct iov_iter *i) +{ + return i->copy_mc; +} +#else +static inline void iov_iter_set_copy_mc(struct iov_iter *i) { } +static inline void iov_iter_clear_copy_mc(struct iov_iter *i) {} +static inline bool iov_iter_is_copy_mc(const struct iov_iter *i) +{ + return false; +} +#endif + /* * Total number of bytes covered by an iovec. * @@ -359,6 +384,7 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction, .iter_type = ITER_UBUF, .user_backed = true, .data_source = direction, + .copy_mc = false, .ubuf = buf, .count = count, .nr_segs = 1 diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 6d0203a3c00a..84bdb09e64a7 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -291,6 +291,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction, .nofault = false, .user_backed = true, .data_source = direction, + .copy_mc = false, .__iov = iov, .nr_segs = nr_segs, .iov_offset = 0, @@ -371,6 +372,14 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) EXPORT_SYMBOL_GPL(_copy_mc_to_iter); #endif /* CONFIG_ARCH_HAS_COPY_MC */ +static void *memcpy_from_iter(struct iov_iter *i, void *to, const void *from, + size_t size) +{ + if (iov_iter_is_copy_mc(i)) + return (void *)copy_mc_to_kernel(to, from, size); + return memcpy(to, from, size); +} + size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) { if (WARN_ON_ONCE(!i->data_source)) @@ -380,7 +389,7 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) might_fault(); iterate_and_advance(i, bytes, base, len, off, copyin(addr + off, base, len), - memcpy(addr + off, base, len) + memcpy_from_iter(i, addr + off, base, len) ) return bytes; @@ -571,7 +580,7 @@ size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t byt } iterate_and_advance(i, bytes, base, len, off, copyin(p + off, base, len), - memcpy(p + off, base, len) + memcpy_from_iter(i, p + off, base, len) ) kunmap_atomic(kaddr); return bytes; @@ -705,6 +714,7 @@ void iov_iter_kvec(struct iov_iter *i, unsigned int direction, *i = (struct iov_iter){ .iter_type = ITER_KVEC, .data_source = direction, + .copy_mc = false, .kvec = kvec, .nr_segs = nr_segs, .iov_offset = 0, @@ -721,6 +731,7 @@ void iov_iter_bvec(struct iov_iter *i, unsigned int direction, *i = (struct iov_iter){ .iter_type = ITER_BVEC, .data_source = direction, + .copy_mc = false, .bvec = bvec, .nr_segs = nr_segs, .iov_offset = 0, @@ -749,6 +760,7 @@ void iov_iter_xarray(struct iov_iter *i, unsigned int direction, *i = (struct iov_iter) { .iter_type = ITER_XARRAY, .data_source = direction, + .copy_mc = false, .xarray = xarray, .xarray_start = start, .count = count, @@ -772,6 +784,7 @@ void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) *i = (struct iov_iter){ .iter_type = ITER_DISCARD, .data_source = false, + .copy_mc = false, .count = count, .iov_offset = 0 };