From 2039e6acaf94d83ec6b6d9f3d0bce7ea1f099918 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 22 Dec 2015 17:54:24 -0700 Subject: [PATCH] x86/mm/pat: Change free_memtype() to support shrinking case Using mremap() to shrink the map size of a VM_PFNMAP range causes the following error message, and leaves the pfn range allocated. x86/PAT: test:3493 freeing invalid memtype [mem 0x483200000-0x4863fffff] This is because rbt_memtype_erase(), called from free_memtype() with spin_lock held, only supports to free a whole memtype node in memtype_rbroot. Therefore, this patch changes rbt_memtype_erase() to support a request that shrinks the size of a memtype node for mremap(). memtype_rb_exact_match() is renamed to memtype_rb_match(), and is enhanced to support EXACT_MATCH and END_MATCH in @match_type. Since the memtype_rbroot tree allows overlapping ranges, rbt_memtype_erase() checks with EXACT_MATCH first, i.e. free a whole node for the munmap case. If no such entry is found, it then checks with END_MATCH, i.e. shrink the size of a node from the end for the mremap case. On the mremap case, rbt_memtype_erase() proceeds in two steps, 1) remove the node, and then 2) insert the updated node. This allows proper update of augmented values, subtree_max_end, in the tree. Signed-off-by: Toshi Kani Cc: Ingo Molnar Cc: H. Peter Anvin Cc: Borislav Petkov Cc: stsp@list.ru Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/1450832064-10093-3-git-send-email-toshi.kani@hpe.com Signed-off-by: Thomas Gleixner --- arch/x86/mm/pat.c | 2 +- arch/x86/mm/pat_rbtree.c | 52 +++++++++++++++++++++++++++++++++------- 2 files changed, 44 insertions(+), 10 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 1aca073ba571..031782e74231 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -586,7 +586,7 @@ int free_memtype(u64 start, u64 end) entry = rbt_memtype_erase(start, end); spin_unlock(&memtype_lock); - if (!entry) { + if (IS_ERR(entry)) { pr_info("x86/PAT: %s:%d freeing invalid memtype [mem %#010Lx-%#010Lx]\n", current->comm, current->pid, start, end - 1); return -EINVAL; diff --git a/arch/x86/mm/pat_rbtree.c b/arch/x86/mm/pat_rbtree.c index 63931080366a..2f7702253ccf 100644 --- a/arch/x86/mm/pat_rbtree.c +++ b/arch/x86/mm/pat_rbtree.c @@ -98,8 +98,13 @@ static struct memtype *memtype_rb_lowest_match(struct rb_root *root, return last_lower; /* Returns NULL if there is no overlap */ } -static struct memtype *memtype_rb_exact_match(struct rb_root *root, - u64 start, u64 end) +enum { + MEMTYPE_EXACT_MATCH = 0, + MEMTYPE_END_MATCH = 1 +}; + +static struct memtype *memtype_rb_match(struct rb_root *root, + u64 start, u64 end, int match_type) { struct memtype *match; @@ -107,7 +112,12 @@ static struct memtype *memtype_rb_exact_match(struct rb_root *root, while (match != NULL && match->start < end) { struct rb_node *node; - if (match->start == start && match->end == end) + if ((match_type == MEMTYPE_EXACT_MATCH) && + (match->start == start) && (match->end == end)) + return match; + + if ((match_type == MEMTYPE_END_MATCH) && + (match->start < start) && (match->end == end)) return match; node = rb_next(&match->rb); @@ -117,7 +127,7 @@ static struct memtype *memtype_rb_exact_match(struct rb_root *root, match = NULL; } - return NULL; /* Returns NULL if there is no exact match */ + return NULL; /* Returns NULL if there is no match */ } static int memtype_rb_check_conflict(struct rb_root *root, @@ -210,12 +220,36 @@ struct memtype *rbt_memtype_erase(u64 start, u64 end) { struct memtype *data; - data = memtype_rb_exact_match(&memtype_rbroot, start, end); - if (!data) - goto out; + /* + * Since the memtype_rbroot tree allows overlapping ranges, + * rbt_memtype_erase() checks with EXACT_MATCH first, i.e. free + * a whole node for the munmap case. If no such entry is found, + * it then checks with END_MATCH, i.e. shrink the size of a node + * from the end for the mremap case. + */ + data = memtype_rb_match(&memtype_rbroot, start, end, + MEMTYPE_EXACT_MATCH); + if (!data) { + data = memtype_rb_match(&memtype_rbroot, start, end, + MEMTYPE_END_MATCH); + if (!data) + return ERR_PTR(-EINVAL); + } + + if (data->start == start) { + /* munmap: erase this node */ + rb_erase_augmented(&data->rb, &memtype_rbroot, + &memtype_rb_augment_cb); + } else { + /* mremap: update the end value of this node */ + rb_erase_augmented(&data->rb, &memtype_rbroot, + &memtype_rb_augment_cb); + data->end = start; + data->subtree_max_end = data->end; + memtype_rb_insert(&memtype_rbroot, data); + return NULL; + } - rb_erase_augmented(&data->rb, &memtype_rbroot, &memtype_rb_augment_cb); -out: return data; } -- 2.45.2