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From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org,
	x86@kernel.org, akpm@linux-foundation.org, keescook@chromium.org,
	shakeelb@google.com, vbabka@suse.cz, rppt@kernel.org
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>,
	linux-mm@kvack.org, linux-hardening@vger.kernel.org,
	kernel-hardening@lists.openwall.com, ira.weiny@intel.com,
	dan.j.williams@intel.com, linux-kernel@vger.kernel.org
Subject: [RFC PATCH v2 08/19] x86/mm/cpa: Add get_grouped_page_atomic()
Date: Mon, 30 Aug 2021 16:59:16 -0700	[thread overview]
Message-ID: <20210830235927.6443-9-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20210830235927.6443-1-rick.p.edgecombe@intel.com>

For PKS tables, some page table allocations are made with GFP_ATOMIC,
which up to now has not been supported.

Grouped pages may often have pages in the cache, which can be retrieved
without sleeping, however if the cache is empty, it will need try to
replenish from the normal page allocator. Just passing GFP_ATOMIC in
addition to the configure GFP is not ideal because it may try to grab a
whole huge page size page which will stress the atomic reserves.

So instead create new logic that will only try to allocate a single page
and convert it.

Expose this atomic logic in a new function get_grouped_page_atomic(),
instead of allowing a flag to be passed in. This is so it doesn't look
like any GFP flag can get passed in and result in behavior like normal
allocations.

In the case of PKS tables conversion of the page allocated atomically,
set_memory() calls cannot usually be made in atomic context because
pages may need to be allocated, but PKS tables has its own reserve of
direct map tables so pages can be converted to PKS protected in atomic
context.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
 arch/x86/include/asm/set_memory.h |  1 +
 arch/x86/mm/pat/set_memory.c      | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index eaac7e3e08bf..e0516651698a 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -153,6 +153,7 @@ int init_grouped_page_cache(struct grouped_page_cache *gpc, gfp_t gfp,
 			    gpc_callback pre_add_to_cache,
 			    gpc_callback pre_shrink_free);
 struct page *get_grouped_page(int node, struct grouped_page_cache *gpc);
+struct page *get_grouped_page_atomic(int node, struct grouped_page_cache *gpc);
 void free_grouped_page(struct grouped_page_cache *gpc, struct page *page);
 
 #endif /* _ASM_X86_SET_MEMORY_H */
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 72a465e37648..c51792a797cb 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -2496,6 +2496,32 @@ struct page *get_grouped_page(int node, struct grouped_page_cache *gpc)
 	return __replenish_grouped_pages(gpc, node);
 }
 
+struct page *get_grouped_page_atomic(int node, struct grouped_page_cache *gpc)
+{
+	struct page *page;
+
+	if (in_interrupt()) {
+		pr_warn_once("grouped pages: Cannot allocate grouped page in interrupt");
+		return NULL;
+	}
+
+	/* First see if there are any grouped pages already in the cache */
+	page = __remove_first_page(gpc, node);
+
+	/*
+	 * If there wasn't one in the cache, allocate only a single page to not
+	 * stress the reserves.
+	 */
+	if (!page)
+		page = __alloc_page_order(node, gpc->gfp | GFP_ATOMIC, 0);
+
+	/* Convert the single page if configured for this cache */
+	if (!page || __try_convert(gpc, page, 1))
+		return NULL;
+
+	return page;
+}
+
 void free_grouped_page(struct grouped_page_cache *gpc, struct page *page)
 {
 	INIT_LIST_HEAD(&page->lru);
-- 
2.17.1


  parent reply	other threads:[~2021-08-31  0:00 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 23:59 [RFC PATCH v2 00/19] PKS write protected page tables Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 01/19] list: Support getting most recent element in list_lru Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 02/19] list: Support list head not in object for list_lru Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 03/19] x86/mm/cpa: Add grouped page allocations Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 04/19] mm: Explicitly zero page table lock ptr Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 05/19] x86, mm: Use cache of page tables Rick Edgecombe
2021-08-31  8:40   ` Mike Rapoport
2021-08-31 19:09     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 06/19] x86/mm/cpa: Add perm callbacks to grouped pages Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 07/19] x86/cpufeatures: Add feature for pks tables Rick Edgecombe
2021-08-30 23:59 ` Rick Edgecombe [this message]
2021-08-30 23:59 ` [RFC PATCH v2 09/19] x86/mm: Support GFP_ATOMIC in alloc_table_node() Rick Edgecombe
2021-08-31  8:32   ` Mike Rapoport
2021-08-30 23:59 ` [RFC PATCH v2 10/19] x86/mm: Use alloc_table() for fill_pte(), etc Rick Edgecombe
2021-08-31  8:47   ` Mike Rapoport
2021-08-31 18:48     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 11/19] mm/sparsemem: Use alloc_table() for table allocations Rick Edgecombe
2021-08-31  8:55   ` Mike Rapoport
2021-08-31 18:25     ` Edgecombe, Rick P
2021-09-01  7:22       ` Mike Rapoport
2021-09-02 13:56         ` Vlastimil Babka
2021-08-30 23:59 ` [RFC PATCH v2 12/19] x86/mm: Use free_table in unmap path Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 13/19] mm/debug_vm_page_table: Use setters instead of WRITE_ONCE Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 14/19] x86/efi: Toggle table protections when copying Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 15/19] x86/mm/cpa: Add set_memory_pks() Rick Edgecombe
2021-08-30 23:59 ` [RFC PATCH v2 16/19] x86/mm: Protect page tables with PKS Rick Edgecombe
2021-08-31  8:56   ` Mike Rapoport
2021-08-31 17:55     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 17/19] x86/mm/cpa: PKS protect direct map page tables Rick Edgecombe
2021-08-31 10:14   ` Mike Rapoport
2021-08-31 17:58     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 18/19] x86/mm: Add PKS table soft mode Rick Edgecombe
2021-08-31  3:49   ` Randy Dunlap
2021-08-31 17:55     ` Edgecombe, Rick P
2021-08-30 23:59 ` [RFC PATCH v2 19/19] x86/mm: Add PKS table debug checking Rick Edgecombe

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