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[50.53.21.37]) by smtp.gmail.com with ESMTPSA id d12-v6sm24980289pfk.69.2018.09.10.16.43.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 10 Sep 2018 16:43:42 -0700 (PDT) Subject: [PATCH 1/4] mm: Provide kernel parameter to allow disabling page init poisoning From: Alexander Duyck To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org Date: Mon, 10 Sep 2018 16:43:41 -0700 Message-ID: <20180910234341.4068.26882.stgit@localhost.localdomain> In-Reply-To: <20180910232615.4068.29155.stgit@localhost.localdomain> References: <20180910232615.4068.29155.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pavel.tatashin@microsoft.com, mhocko@suse.com, dave.hansen@intel.com, jglisse@redhat.com, akpm@linux-foundation.org, mingo@kernel.org, kirill.shutemov@linux.intel.com Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP From: Alexander Duyck On systems with a large amount of memory it can take a significant amount of time to initialize all of the page structs with the PAGE_POISON_PATTERN value. I have seen it take over 2 minutes to initialize a system with over 12GB of RAM. In order to work around the issue I had to disable CONFIG_DEBUG_VM and then the boot time returned to something much more reasonable as the arch_add_memory call completed in milliseconds versus seconds. However in doing that I had to disable all of the other VM debugging on the system. In order to work around a kernel that might have CONFIG_DEBUG_VM enabled on a system that has a large amount of memory I have added a new kernel parameter named "page_init_poison" that can be set to "off" in order to disable it. Signed-off-by: Alexander Duyck Reviewed-by: Pavel Tatashin --- Documentation/admin-guide/kernel-parameters.txt | 8 ++++++++ include/linux/page-flags.h | 8 ++++++++ mm/debug.c | 16 ++++++++++++++++ mm/memblock.c | 5 ++--- mm/sparse.c | 4 +--- 5 files changed, 35 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 64a3bf54b974..7b21e0b9c394 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3047,6 +3047,14 @@ off: turn off poisoning (default) on: turn on poisoning + page_init_poison= [KNL] Boot-time parameter changing the + state of poisoning of page structures during early + boot. Used to verify page metadata is not accessed + prior to initialization. Available with + CONFIG_DEBUG_VM=y. + off: turn off poisoning + on: turn on poisoning (default) + panic= [KNL] Kernel behaviour on panic: delay timeout > 0: seconds before rebooting timeout = 0: wait forever diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 74bee8cecf4c..d00216cf00f8 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -162,6 +162,14 @@ static inline int PagePoisoned(const struct page *page) return page->flags == PAGE_POISON_PATTERN; } +#ifdef CONFIG_DEBUG_VM +void page_init_poison(struct page *page, size_t size); +#else +static inline void page_init_poison(struct page *page, size_t size) +{ +} +#endif + /* * Page flags policies wrt compound pages * diff --git a/mm/debug.c b/mm/debug.c index 38c926520c97..c5420422c0b5 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -175,4 +175,20 @@ void dump_mm(const struct mm_struct *mm) ); } +static bool page_init_poisoning __read_mostly = true; + +static int __init page_init_poison_param(char *buf) +{ + if (!buf) + return -EINVAL; + return strtobool(buf, &page_init_poisoning); +} +early_param("page_init_poison", page_init_poison_param); + +void page_init_poison(struct page *page, size_t size) +{ + if (page_init_poisoning) + memset(page, PAGE_POISON_PATTERN, size); +} +EXPORT_SYMBOL_GPL(page_init_poison); #endif /* CONFIG_DEBUG_VM */ diff --git a/mm/memblock.c b/mm/memblock.c index 237944479d25..a85315083b5a 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1444,10 +1444,9 @@ void * __init memblock_virt_alloc_try_nid_raw( ptr = memblock_virt_alloc_internal(size, align, min_addr, max_addr, nid); -#ifdef CONFIG_DEBUG_VM if (ptr && size > 0) - memset(ptr, PAGE_POISON_PATTERN, size); -#endif + page_init_poison(ptr, size); + return ptr; } diff --git a/mm/sparse.c b/mm/sparse.c index 10b07eea9a6e..67ad061f7fb8 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -696,13 +696,11 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat, goto out; } -#ifdef CONFIG_DEBUG_VM /* * Poison uninitialized struct pages in order to catch invalid flags * combinations. */ - memset(memmap, PAGE_POISON_PATTERN, sizeof(struct page) * PAGES_PER_SECTION); -#endif + page_init_poison(memmap, sizeof(struct page) * PAGES_PER_SECTION); section_mark_present(ms); sparse_init_one_section(ms, section_nr, memmap, usemap);