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Thu, 13 May 2021 10:55:14 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id E8EE56144B; Thu, 13 May 2021 10:55:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620903311; bh=+pWwtblnPpVpGB/q2c4WYbGx3gEXQhVW/vwXOmX5ACg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XW+hQBNXiueUibidwJKNIlhUVK834VZIqdCAgkXR0BLOpwFDtpJVH8Rn8QINyH2an ibPiJYAPq177mw0NLMakS0ccT00vy6BehhNy8JngeBM8rZ6eoL17oHM7ZzbScIFOeB fGWMUcd0sUgCLwhGEsBrkwxDGWlVPJPXwrBaCZVComqG2Hl2N5Bqt2xHwFP2Ob05to ICwWNzR78fpTudi0PSnk40FOr+k12uZKsV/2EbSMrlHWfxuirjo5YThWH6VeYL8A94 hkT7po03BZfQb/AiKsMHUdosiqwbny0LHIBvRokF28tz1qSv5OIkmYzaJgJPmi0CU/ EHxj555a9XjHg== Date: Thu, 13 May 2021 13:55:02 +0300 From: Mike Rapoport To: Kefeng Wang Cc: David Hildenbrand , linux-arm-kernel@lists.infradead.org, Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , Marc Zyngier , Mark Rutland , Mike Rapoport , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: arm32: panic in move_freepages (Was [PATCH v2 0/4] arm64: drop pfn_valid_within() and simplify pfn_valid()) Message-ID: References: <82cfbb7f-dd4f-12d8-dc76-847f06172200@huawei.com> <33c67e13-dc48-9a2f-46d8-a532e17380fb@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210513_035512_656388_0E98C129 X-CRM114-Status: GOOD ( 55.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, May 13, 2021 at 11:44:00AM +0800, Kefeng Wang wrote: > On 2021/5/12 16:26, Mike Rapoport wrote: > > On Wed, May 12, 2021 at 11:08:14AM +0800, Kefeng Wang wrote: > > > > > > On 2021/5/11 16:48, Mike Rapoport wrote: > > > > On Mon, May 10, 2021 at 11:10:20AM +0800, Kefeng Wang wrote: > > > > > > > > > > > > The memory is not continuous, see MEMBLOCK: > > > > > > > memory size = 0x4c0fffff reserved size = 0x027ef058 > > > > > > > memory.cnt = 0xa > > > > > > > memory[0x0] [0x80a00000-0x855fffff], 0x04c00000 bytes flags: 0x0 > > > > > > > memory[0x1] [0x86a00000-0x87dfffff], 0x01400000 bytes flags: 0x0 > > > > > > > memory[0x2] [0x8bd00000-0x8c4fffff], 0x00800000 bytes flags: 0x0 > > > > > > > memory[0x3] [0x8e300000-0x8ecfffff], 0x00a00000 bytes flags: 0x0 > > > > > > > memory[0x4] [0x90d00000-0xbfffffff], 0x2f300000 bytes flags: 0x0 > > > > > > > memory[0x5] [0xcc000000-0xdc9fffff], 0x10a00000 bytes flags: 0x0 > > > > > > > memory[0x6] [0xde700000-0xde9fffff], 0x00300000 bytes flags: 0x0 > > > > > > > ... > > > > > > > > > > > > > > The pfn_range [0xde600,0xde700] => addr_range [0xde600000,0xde700000] > > > > > > > is not available memory, and we won't create memmap , so with or without > > > > > > > your patch, we can't see the range in free_memmap(), right? > > > > > > > > > > > > This is not available memory and we won't see the reange in free_memmap(), > > > > > > but we still should create memmap for it and that's what my patch tried to > > > > > > do. > > > > > > > > > > > > There are a lot of places in core mm that operate on pageblocks and > > > > > > free_unused_memmap() should make sure that any pageblock has a valid memory > > > > > > map. > > > > > > > > > > > > Currently, that's not the case when SPARSEMEM=y and my patch tried to fix > > > > > > it. > > > > > > > > > > > > Can you please send log with my patch applied and with the printing of > > > > > > ranges that are freed in free_unused_memmap() you've used in previous > > > > > > mails? > > > > > > > > > with your patch[1] and debug print in free_memmap, > > > > > ----> free_memmap, start_pfn = 85800, 85800000 end_pfn = 86800, 86800000 > > > > > ----> free_memmap, start_pfn = 8c800, 8c800000 end_pfn = 8e000, 8e000000 > > > > > ----> free_memmap, start_pfn = 8f000, 8f000000 end_pfn = 90000, 90000000 > > > > > ----> free_memmap, start_pfn = dcc00, dcc00000 end_pfn = de400, de400000 > > > > > ----> free_memmap, start_pfn = dec00, dec00000 end_pfn = e0000, e0000000 > > > > > ----> free_memmap, start_pfn = e0c00, e0c00000 end_pfn = e4000, e4000000 > > > > > ----> free_memmap, start_pfn = f7000, f7000000 end_pfn = f8000, f8000000 > > > > > > > > It seems that freeing of the memory map is suboptimal still because that > > > > code was not designed for memory layout that has more holes than Swiss > > > > cheese. > > > > > > > > Still, the range [0xde600,0xde700] is not freed and there should be struct > > > > pages for this range. > > > > > > > > Can you add > > > > > > > > dump_page(pfn_to_page(0xde600), ""); > > > > > > > > say, in the end of memblock_free_all()? > > > > > > > The range [0xde600,0xde700] is not memory, so it won't create struct page > > > for it when sparse_init? > > > > sparse_init() indeed does not create memory map for unpopulated memory, but > > it has pretty coarse granularity, i.e. 64M in your configuration. A hole > > should be at least 64M in order to skip allocation of the memory map for > > it. > > > > For example, your memory layout has a hole of 192M at pfn 0xc0000 and this > > hole won't have the memory map. > > > > However the hole 0xdca00 - 0xde70 will still have a memory map in the > > section that covers 0xdc000 - 0xe0000. > > > > I've tried outline this in a sketch below, hope it helps. > > > > Memory: > > c0000 cc000 dca00 > > --------------------------+ +--------------------------+ +----+ > > memory bank |<- hole ->| memory bank | | mb | > > --------------------------+ +--------------------------+ +----+ > > de700 dea00 > > > > Memory map: > > > > b0000 b4000 c0000 cc000 d0000 d8000 dc000 > > +--------+--------+- ... -+ +--------+- ... -+--------+---------+ > > | memmap | memmap | ... |<- hole ->| memmap | ... | memmap | memmap | > > +--------+--------+- ... -+ +--------+- ... -+--------+---------+ > > > > > Thanks for the sketch, it is more clear, > > > > After apply patch[1], the dump_page log, > > > > > > page:ef3cc000 is uninitialized and poisoned > > > raw: ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff > > > page dumped because: > > > > This means that there is a memory map entry, and it got poisoned during the > > initialization and never got reinitialized to sensible values, which would > > be PageReserved() in this case. > > > > I believe this was fixed by commit 0740a50b9baa ("mm/page_alloc.c: refactor > > initialization of struct page for holes in memory layout") in the mainline > > tree. > > > > Can you backport it to your 5.10 tree and check if it helps? > Hi Mike, the 0740a50b9baa is already in 5.10, tags/v5.10.24~5 Ah, you are using stable 5.10.y. > commit 4c84191cbc3eff49568d3c5cccb628fa382cf7fb > Author: Mike Rapoport > Date: Fri Mar 12 21:07:12 2021 -0800 > > mm/page_alloc.c: refactor initialization of struct page for holes in > memory layout > > commit 0740a50b9baa4472cfb12442df4b39e2712a64a4 upstream. > > but check init_unavailable_range(), we need deal with the hole in the > range of one pageblock. > > For our scene, pageblock range: 0xde600,0xde7ff, but the available pfn begin > with 0xde700. > > If pfn(eg, 0xde600) is not valid, the step in init_unavailable_range is > pageblock_nr_pages, and ALIGN_DOWN(pfn, pageblock_nr_pages) from 0xde600 > to 0xde700 is same, so the page range for pfn [0xde600,0xde700] won't be > initialized. The pfn 0xde600 is valid in the sense that there is a memory map for that pfn. Yet, with ARM's custom pfn_valid() will treat it as invalid because there is a hole. > After add the following patch, the oom test could passed, > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index aaa1655cf682..0c7e04f86f9f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6484,13 +6484,14 @@ static u64 __meminit init_unavailable_range(unsigned > long spfn, > unsigned long epfn, > int zone, int node) > { > - unsigned long pfn; > + unsigned long pfn, pfn_down; > + unsigned long epfn_down = ALIGN_DOWN(epfn, pageblock_nr_pages); > u64 pgcnt = 0; > > for (pfn = spfn; pfn < epfn; pfn++) { > - if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) { > - pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) > - + pageblock_nr_pages - 1; > + pfn_down = ALIGN_DOWN(pfn, pageblock_nr_pages); > + if (!pfn_valid(pfn_down) && pfn_down != epfn_down) { > + pfn = pfn_down + pageblock_nr_pages - 1; > continue; > } > __init_single_page(pfn_to_page(pfn), pfn, zone, node); I'd rather prefer to keep init_unavailable_range() and the assumption that the memory map always covers an entire pageblock. Can you please try the below hack. Essentially, it makes arm with SPARSEMEM to use the generic pfn_valid() and updates the freeing of the memory map to have the entire pageblocks covered. If this works I'll send formal patches for those changes. diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 24804f11302d..86ee711a3fdb 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -73,7 +73,7 @@ config ARM select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL select HAVE_ARCH_MMAP_RND_BITS if MMU - select HAVE_ARCH_PFN_VALID +# select HAVE_ARCH_PFN_VALID select HAVE_ARCH_SECCOMP select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT select HAVE_ARCH_THREAD_STRUCT_WHITELIST diff --git a/mm/memblock.c b/mm/memblock.c index 504435753259..0d7bef1b49c3 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1928,9 +1928,11 @@ static void __init free_unused_memmap(void) unsigned long start, end, prev_end = 0; int i; +#ifndef CONFIG_ARM if (!IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) || IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) return; +#endif /* * This relies on each bank being in address order. @@ -1943,14 +1945,13 @@ static void __init free_unused_memmap(void) * due to SPARSEMEM sections which aren't present. */ start = min(start, ALIGN(prev_end, PAGES_PER_SECTION)); -#else +#endif /* * Align down here since the VM subsystem insists that the * memmap entries are valid from the bank start aligned to * MAX_ORDER_NR_PAGES. */ start = round_down(start, MAX_ORDER_NR_PAGES); -#endif /* * If we had a previous bank, and there is a space > Before: > On node 0 totalpages: 311551 > Normal zone: 1230 pages used for memmap > Normal zone: 0 pages reserved > Normal zone: 157440 pages, LIFO batch:31 > Normal zone: 16384 pages in unavailable ranges > HighMem zone: 154111 pages, LIFO batch:31 > HighMem zone: 1 pages in unavailable ranges > > page:ef3cc000 is uninitialized and poisoned > raw: ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff > > After: > On node 0 totalpages: 311551 > Normal zone: 1230 pages used for memmap > Normal zone: 0 pages reserved > Normal zone: 157440 pages, LIFO batch:31 > Normal zone: 17152 pages in unavailable ranges > HighMem zone: 154111 pages, LIFO batch:31 > HighMem zone: 513 pages in unavailable ranges > ... > page:(ptrval) refcount:1 mapcount:0 mapping:00000000 index:0x0 pfn:0xde600 > flags: 0xdd001000(reserved) > raw: dd001000 ef3cc004 ef3cc004 00000000 00000000 00000000 ffffffff 00000001 > -- Sincerely yours, Mike. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel