[PATCH] mm/vmalloc: Check absolute error return from vmap_[p4d|pud|pmd|pte]_range()

[Anshuman Khandual]

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.edgeco...@intel.com>
Cc: Andrey Ryabinin <aryabi...@virtuozzo.com>
Cc: Mike Rapoport <r...@linux.ibm.com>
Cc: Roman Gushchin <g...@fb.com>
Cc: Michal Hocko <mho...@suse.com>
Cc: Roman Penyaev <rpeny...@suse.de>
Cc: "Uladzislau Rezki (Sony)" <ure...@gmail.com>
Cc: Andrew Morton <a...@linux-foundation.org>

Signed-off-by: Anshuman Khandual <anshuman.khand...@arm.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