linux-kernel - [PATCH] mm/vmalloc: Check absolute error return from vmap_[p4d|pud|pmd|pte]

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Message-Id: <1560413551-17460-1-git-send-email-anshuman.khandual@arm.com>
Date:   Thu, 13 Jun 2019 13:42:31 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Roman Gushchin <guro@...com>, Michal Hocko <mhocko@...e.com>,
        Roman Penyaev <rpenyaev@...e.de>,
        "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] mm/vmalloc: Check absolute error return from vmap_[p4d|pud|pmd|pte]_range()

vmap_pte_range() returns an -EBUSY when it encounters a non-empty PTE. But
currently vmap_pmd_range() unifies both -EBUSY and -ENOMEM return code as
-ENOMEM and send it up the call chain which is wrong. Interestingly enough
vmap_page_range_noflush() tests for the absolute error return value from
vmap_p4d_range() but it does not help because -EBUSY has been merged with
-ENOMEM. So all it can return is -ENOMEM. Fix this by testing for absolute
error return from vmap_pmd_range() all the way up to vmap_p4d_range().

Cc: Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Mike Rapoport <rppt@...ux.ibm.com>
Cc: Roman Gushchin <guro@...com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Roman Penyaev <rpenyaev@...e.de>
Cc: "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>

Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
 mm/vmalloc.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 7350a124524b..6c7dd8df23c3 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -165,14 +165,16 @@ static int vmap_pmd_range(pud_t *pud, unsigned long addr,
 {
 	pmd_t *pmd;
 	unsigned long next;
+	int err = 0;
 
 	pmd = pmd_alloc(&init_mm, pud, addr);
 	if (!pmd)
 		return -ENOMEM;
 	do {
 		next = pmd_addr_end(addr, end);
-		if (vmap_pte_range(pmd, addr, next, prot, pages, nr))
-			return -ENOMEM;
+		err = vmap_pte_range(pmd, addr, next, prot, pages, nr);
+		if (err)
+			return err;
 	} while (pmd++, addr = next, addr != end);
 	return 0;
 }
@@ -182,14 +184,16 @@ static int vmap_pud_range(p4d_t *p4d, unsigned long addr,
 {
 	pud_t *pud;
 	unsigned long next;
+	int err = 0;
 
 	pud = pud_alloc(&init_mm, p4d, addr);
 	if (!pud)
 		return -ENOMEM;
 	do {
 		next = pud_addr_end(addr, end);
-		if (vmap_pmd_range(pud, addr, next, prot, pages, nr))
-			return -ENOMEM;
+		err = vmap_pmd_range(pud, addr, next, prot, pages, nr);
+		if (err)
+			return err;
 	} while (pud++, addr = next, addr != end);
 	return 0;
 }
@@ -199,14 +203,16 @@ static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
 {
 	p4d_t *p4d;
 	unsigned long next;
+	int err = 0;
 
 	p4d = p4d_alloc(&init_mm, pgd, addr);
 	if (!p4d)
 		return -ENOMEM;
 	do {
 		next = p4d_addr_end(addr, end);
-		if (vmap_pud_range(p4d, addr, next, prot, pages, nr))
-			return -ENOMEM;
+		err = vmap_pud_range(p4d, addr, next, prot, pages, nr);
+		if (err)
+			return err;
 	} while (p4d++, addr = next, addr != end);
 	return 0;
 }
-- 
2.20.1