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 3A38A224222; Tue, 29 Apr 2025 20:30:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745958625; cv=none; b=Ptoy3q1zIhxibAiKcjv4S6+I5SeiksWHFOTvPR/JqHDVoj/ogDhCEVQ+2DmkrldA96cl+M97bArnjdkZmjnPydhryLnGgQ95v/qCc7mULDud0dY9ZnKrRghrp40XgSMMJ8wHtFqoIszlObzZvd0oCOGmBOlqfKZDIscVGPNcKVA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745958625; c=relaxed/simple; bh=L+xHPu2WFbG7EX+zFMLeWxjzB7da8Hhj5jBVRXZsXHk=; h=Date:To:From:Subject:Message-Id; b=liASfDWY6bTLHTnC8kxUeB3ix8QioZNTgrAaMHGXaV6QuX6bQCYUpQSrapb4+poKoIS/Tkuzqp2f5+NVZPZ9bG6XBAlnbi/udQg0tz4B4rOaJvFphkIr7n0Yv0UXEdPBukXHYiI5ytXJ5+PdzsD9o2ayUcpaPrI4CsSsolQVpU4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=TqfoIv7k; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="TqfoIv7k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DEE72C4CEE3; Tue, 29 Apr 2025 20:30:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1745958625; bh=L+xHPu2WFbG7EX+zFMLeWxjzB7da8Hhj5jBVRXZsXHk=; h=Date:To:From:Subject:From; b=TqfoIv7kONLSmzauG7kbP7bH3bKeip3yPBJXGv5eco3AM2akp/bmJ6QiRAxMN2gh5 tz9D+n4j7hMDl9tIwdAmzVPaji1LMSXzyvFzm9fz3pt4DWUGoKQAZTVaJZPYPfNWqF 41FuTb+BbEyhxUGimYzd1EGgKYh1DYs1yuQ9a6oc= Date: Tue, 29 Apr 2025 13:30:24 -0700 To: mm-commits@vger.kernel.org,vincenzo.frascino@arm.com,stable@vger.kernel.org,ryabinin.a.a@gmail.com,glider@google.com,dvyukov@google.com,dja@axtens.net,andreyknvl@gmail.com,agordeev@linux.ibm.com,akpm@linux-foundation.org From: Andrew Morton Subject: + kasan-avoid-sleepable-page-allocation-from-atomic-context.patch added to mm-hotfixes-unstable branch Message-Id: <20250429203024.DEE72C4CEE3@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: kasan: avoid sleepable page allocation from atomic context has been added to the -mm mm-hotfixes-unstable branch. Its filename is kasan-avoid-sleepable-page-allocation-from-atomic-context.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kasan-avoid-sleepable-page-allocation-from-atomic-context.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Alexander Gordeev Subject: kasan: avoid sleepable page allocation from atomic context Date: Tue, 29 Apr 2025 18:08:41 +0200 apply_to_pte_range() enters the lazy MMU mode and then invokes kasan_populate_vmalloc_pte() callback on each page table walk iteration. However, the callback can go into sleep when trying to allocate a single page, e.g. if an architecutre disables preemption on lazy MMU mode enter. On s390 with the call sequences arch_enter_lazy_mmu_mode() -> preempt_enable() and arch_leave_lazy_mmu_mode() -> preempt_disable(), such a crash occurs: [ 553.332108] preempt_count: 1, expected: 0 [ 553.332117] no locks held by multipathd/2116. [ 553.332128] CPU: 24 PID: 2116 Comm: multipathd Kdump: loaded Tainted: [ 553.332139] Hardware name: IBM 3931 A01 701 (LPAR) [ 553.332146] Call Trace: [ 553.332152] [<00000000158de23a>] dump_stack_lvl+0xfa/0x150 [ 553.332167] [<0000000013e10d12>] __might_resched+0x57a/0x5e8 [ 553.332178] [<00000000144eb6c2>] __alloc_pages+0x2ba/0x7c0 [ 553.332189] [<00000000144d5cdc>] __get_free_pages+0x2c/0x88 [ 553.332198] [<00000000145663f6>] kasan_populate_vmalloc_pte+0x4e/0x110 [ 553.332207] [<000000001447625c>] apply_to_pte_range+0x164/0x3c8 [ 553.332218] [<000000001448125a>] apply_to_pmd_range+0xda/0x318 [ 553.332226] [<000000001448181c>] __apply_to_page_range+0x384/0x768 [ 553.332233] [<0000000014481c28>] apply_to_page_range+0x28/0x38 [ 553.332241] [<00000000145665da>] kasan_populate_vmalloc+0x82/0x98 [ 553.332249] [<00000000144c88d0>] alloc_vmap_area+0x590/0x1c90 [ 553.332257] [<00000000144ca108>] __get_vm_area_node.constprop.0+0x138/0x260 [ 553.332265] [<00000000144d17fc>] __vmalloc_node_range+0x134/0x360 [ 553.332274] [<0000000013d5dbf2>] alloc_thread_stack_node+0x112/0x378 [ 553.332284] [<0000000013d62726>] dup_task_struct+0x66/0x430 [ 553.332293] [<0000000013d63962>] copy_process+0x432/0x4b80 [ 553.332302] [<0000000013d68300>] kernel_clone+0xf0/0x7d0 [ 553.332311] [<0000000013d68bd6>] __do_sys_clone+0xae/0xc8 [ 553.332400] [<0000000013d68dee>] __s390x_sys_clone+0xd6/0x118 [ 553.332410] [<0000000013c9d34c>] do_syscall+0x22c/0x328 [ 553.332419] [<00000000158e7366>] __do_syscall+0xce/0xf0 [ 553.332428] [<0000000015913260>] system_call+0x70/0x98 Instead of allocating single pages per-PTE, bulk-allocate the shadow memory prior to applying kasan_populate_vmalloc_pte() callback on a page range. Link: https://lkml.kernel.org/r/573a823565734e1eac3aa128fb9d3506ec918a72.1745940843.git.agordeev@linux.ibm.com Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shadow memory") Signed-off-by: Alexander Gordeev Suggested-by: Andrey Ryabinin Cc: Alexander Gordeev Cc: Daniel Axtens Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Vincenzo Frascino Cc: Signed-off-by: Andrew Morton --- mm/kasan/shadow.c | 65 +++++++++++++++++++++++++++++++++----------- 1 file changed, 49 insertions(+), 16 deletions(-) --- a/mm/kasan/shadow.c~kasan-avoid-sleepable-page-allocation-from-atomic-context +++ a/mm/kasan/shadow.c @@ -292,30 +292,65 @@ void __init __weak kasan_populate_early_ { } +struct vmalloc_populate_data { + unsigned long start; + struct page **pages; +}; + static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, - void *unused) + void *_data) { - unsigned long page; + struct vmalloc_populate_data *data = _data; + struct page *page; + unsigned long pfn; pte_t pte; if (likely(!pte_none(ptep_get(ptep)))) return 0; - page = __get_free_page(GFP_KERNEL); - if (!page) - return -ENOMEM; - - __memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); - pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); + page = data->pages[PFN_DOWN(addr - data->start)]; + pfn = page_to_pfn(page); + __memset(pfn_to_virt(pfn), KASAN_VMALLOC_INVALID, PAGE_SIZE); + pte = pfn_pte(pfn, PAGE_KERNEL); spin_lock(&init_mm.page_table_lock); - if (likely(pte_none(ptep_get(ptep)))) { + if (likely(pte_none(ptep_get(ptep)))) set_pte_at(&init_mm, addr, ptep, pte); - page = 0; - } spin_unlock(&init_mm.page_table_lock); - if (page) - free_page(page); + + return 0; +} + +static int __kasan_populate_vmalloc(unsigned long start, unsigned long end) +{ + unsigned long nr_pages, nr_total = PFN_UP(end - start); + struct vmalloc_populate_data data; + int ret; + + data.pages = (struct page **)__get_free_page(GFP_KERNEL); + if (!data.pages) + return -ENOMEM; + + while (nr_total) { + nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0])); + __memset(data.pages, 0, nr_pages * sizeof(data.pages[0])); + if (nr_pages != alloc_pages_bulk(GFP_KERNEL, nr_pages, data.pages)) { + free_page((unsigned long)data.pages); + return -ENOMEM; + } + + data.start = start; + ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE, + kasan_populate_vmalloc_pte, &data); + if (ret) + return ret; + + start += nr_pages * PAGE_SIZE; + nr_total -= nr_pages; + } + + free_page((unsigned long)data.pages); + return 0; } @@ -348,9 +383,7 @@ int kasan_populate_vmalloc(unsigned long shadow_start = PAGE_ALIGN_DOWN(shadow_start); shadow_end = PAGE_ALIGN(shadow_end); - ret = apply_to_page_range(&init_mm, shadow_start, - shadow_end - shadow_start, - kasan_populate_vmalloc_pte, NULL); + ret = __kasan_populate_vmalloc(shadow_start, shadow_end); if (ret) return ret; _ Patches currently in -mm which might be from agordeev@linux.ibm.com are kasan-avoid-sleepable-page-allocation-from-atomic-context.patch