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] rbt_memtype_erase(), called from free_memtype() with spin_lock held, only accepts to free a whole memtype node in memtype_rbroot. Change rbt_memtype_erase() to accept a request that shrinks the size of a memtype node for mremap(). memtype_rb_exact_match() is renamed to memtype_rb_match(), which now performs exact match or shrink match per match_type. Since the memtype_rbroot tree allows overlapping ranges, rbt_memtype_erase() checks exact match first to ensure the case of freeing a whole node, which is the normal case. For the shrink 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. Reference: https://lkml.org/lkml/2015/10/28/865 Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> --- arch/x86/mm/pat.c | 2 +- arch/x86/mm/pat_rbtree.c | 46 +++++++++++++++++++++++++++++++++++++--------- 2 files changed, 38 insertions(+), 10 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index f3e391e..f277efd 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 6393108..d6faef8 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_SHRINK_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_SHRINK_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 +220,30 @@ 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; + /* Exact match takes precedence over shrink match */ + data = memtype_rb_match(&memtype_rbroot, start, end, + MEMTYPE_EXACT_MATCH); + if (!data) { + data = memtype_rb_match(&memtype_rbroot, start, end, + MEMTYPE_SHRINK_MATCH); + if (!data) + return ERR_PTR(-EINVAL); + } + + if (data->start == start) { + /* Exact match: erase this node */ + rb_erase_augmented(&data->rb, &memtype_rbroot, + &memtype_rb_augment_cb); + } else { + /* Shrink match: 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; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>