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Date: Tue, 10 Aug 2021 18:05:35 +0200 From: Gerald Schaefer <gerald.schaefer@...ux.ibm.com> To: Gavin Shan <gshan@...hat.com> Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, anshuman.khandual@....com, aneesh.kumar@...ux.ibm.com, christophe.leroy@...roup.eu, cai@....pw, catalin.marinas@....com, will@...nel.org, vgupta@...opsys.com, akpm@...ux-foundation.org, chuhu@...hat.com, shan.gavin@...il.com Subject: Re: [PATCH v6 00/12] mm/debug_vm_pgtable: Enhancements On Mon, 9 Aug 2021 17:26:19 +0800 Gavin Shan <gshan@...hat.com> wrote: > There are couple of issues with current implementations and this series > tries to resolve the issues: > > (a) All needed information are scattered in variables, passed to various > test functions. The code is organized in pretty much relaxed fashion. > > (b) The page isn't allocated from buddy during page table entry modifying > tests. The page can be invalid, conflicting to the implementations > of set_xxx_at() on ARM64. The target page is accessed so that the > iCache can be flushed when execution permission is given on ARM64. > Besides, the target page can be unmapped and accessing to it causes > kernel crash. > > "struct pgtable_debug_args" is introduced to address issue (a). For issue > (b), the used page is allocated from buddy in page table entry modifying > tests. The corresponding tets will be skipped if we fail to allocate the > (huge) page. For other test cases, the original page around to kernel > symbol (@start_kernel) is still used. > > The patches are organized as below. PATCH[2-10] could be combined to one > patch, but it will make the review harder: > > PATCH[1] introduces "struct pgtable_debug_args" as place holder of all > needed information. With it, the old and new implementation > can coexist. > PATCH[2-10] uses "struct pgtable_debug_args" in various test functions. > PATCH[11] removes the unused code for old implementation. > PATCH[12] fixes the issue of corrupted page flag for ARM64 Tested on s390, all seems to work fine. Gerald
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