mm/sharepool: Fix sharepool hugepage cgroup uncount error.

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5XQS4
CVE: NA

--------------------------------

If current->flag is set as PF_MEMALLOC, memcgroup will not check
current's allocation against memory use limit, which cause system run
out of memory.

According to
https://lkml.indiana.edu/hypermail/linux/kernel/0911.2/00576.html,
PF_MEMALLOC shall only be used when more memory are sure to be freed as a
result of this allocation.

Do not use PF_MEMALLOC, rather, remove __GFP_RECLAIM from gfp_mask to
ensure no reclaim.
Signed-off-by: NGuo Mengqi <guomengqi3@huawei.com>

include/linux/hugetlb.h

@@ -621,9 +621,11 @@ int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
 #define HUGETLB_ALLOC_NONE             0x00
 #define HUGETLB_ALLOC_NORMAL           0x01    /* normal hugepage */
 #define HUGETLB_ALLOC_BUDDY            0x02    /* buddy hugepage */
-#define HUGETLB_ALLOC_MASK             (HUGETLB_ALLOC_NONE | \
+#define HUGETLB_ALLOC_NORECLAIM        0x04    /* no reclaim */
+#define HUGETLB_ALLOC_MASK             (HUGETLB_ALLOC_NONE   | \
 					HUGETLB_ALLOC_NORMAL | \
-					HUGETLB_ALLOC_BUDDY)
+					HUGETLB_ALLOC_BUDDY  | \
+					HUGETLB_ALLOC_NORECLAIM)
 
 const struct hstate *hugetlb_get_hstate(void);
 struct page *hugetlb_alloc_hugepage(int nid, int flag);

mm/hugetlb.c

@@ -6255,6 +6255,9 @@ struct page *hugetlb_alloc_hugepage(int nid, int flag)
 	if (enable_charge_mighp)
 		gfp_mask |= __GFP_ACCOUNT;
 
+	if (flag & HUGETLB_ALLOC_NORECLAIM)
+		gfp_mask &= ~__GFP_RECLAIM;
+
 	if (flag & HUGETLB_ALLOC_NORMAL)
 		page = hugetlb_alloc_hugepage_normal(h, gfp_mask, nid);
 	else if (flag & HUGETLB_ALLOC_BUDDY)

mm/share_pool.c

@@ -2449,35 +2449,13 @@ static void sp_alloc_fallback(struct sp_area *spa, struct sp_alloc_context *ac)
 static int sp_alloc_populate(struct mm_struct *mm, struct sp_area *spa,
 			     struct sp_alloc_context *ac)
 {
-	int ret = 0;
-	unsigned long sp_addr = spa->va_start;
-	unsigned int noreclaim_flag = 0;
-
-	/*
-	 * The direct reclaim and compact may take a long
-	 * time. As a result, sp mutex will be hold for too
-	 * long time to casue the hung task problem. In this
-	 * case, set the PF_MEMALLOC flag to prevent the
-	 * direct reclaim and compact from being executed.
-	 * Since direct reclaim and compact are not performed
-	 * when the fragmentation is severe or the memory is
-	 * insufficient, 2MB continuous physical pages fail
-	 * to be allocated. This situation is allowed.
-	 */
-	if (spa->is_hugepage)
-		noreclaim_flag = memalloc_noreclaim_save();
-
 	/*
 	 * We are not ignoring errors, so if we fail to allocate
 	 * physical memory we just return failure, so we won't encounter
 	 * page fault later on, and more importantly sp_make_share_u2k()
 	 * depends on this feature (and MAP_LOCKED) to work correctly.
 	 */
-	ret = do_mm_populate(mm, sp_addr, ac->populate, 0);
-	if (spa->is_hugepage)
-		memalloc_noreclaim_restore(noreclaim_flag);
-
-	return ret;
+	return do_mm_populate(mm, spa->va_start, ac->populate, 0);
 }
 
 static long sp_mbind(struct mm_struct *mm, unsigned long start, unsigned long len,
@@ -4233,7 +4211,8 @@ vm_fault_t sharepool_no_page(struct mm_struct *mm,
 
 		page = alloc_huge_page(vma, haddr, 0);
 		if (IS_ERR(page)) {
-			page = hugetlb_alloc_hugepage(node_id, HUGETLB_ALLOC_BUDDY);
+			page = hugetlb_alloc_hugepage(node_id,
+					HUGETLB_ALLOC_BUDDY | HUGETLB_ALLOC_NORECLAIM);
 			if (!page)
 				page = ERR_PTR(-ENOMEM);
 		}