Skip to content

Commit

Permalink
s390/vmem: get rid of memory segment list
Browse files Browse the repository at this point in the history 
I can't come up with a satisfying reason why we still need the memory
segment list. We used to represent in the list:
- boot memory
- standby memory added via add_memory()
- loaded dcss segments

When loading/unloading dcss segments, we already track them in a
separate list and check for overlaps
(arch/s390/mm/extmem.c:segment_overlaps_others()) when loading segments.

The overlap check was introduced for some segments in
commit b2300b9 ("[S390] dcssblk: add >2G DCSSs support and stacked
contiguous DCSSs support.")
and was extended to cover all dcss segments in
commit ca57114 ("s390/extmem: remove code for 31 bit addressing
mode").

Although I doubt that overlaps with boot memory and standby memory
are relevant, let's reshuffle the checks in load_segment() to request
the resource first. This will bail out in case we have overlaps with
other resources (esp. boot memory and standby memory). The order
is now different compared to segment_unload() and segment_unload(), but
that should not matter.

This smells like a leftover from ancient times, let's get rid of it. We
can now convert vmem_remove_mapping() into a void function - everybody
ignored the return value already.

Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20200625150029.45019-1-david@redhat.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [DCSS]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
  • Loading branch information
David Hildenbrand authored and Heiko Carstens committed Jul 1, 2020
1 parent 66a049b commit f05f62d
Show file tree
Hide file tree
Showing 3 changed files with 21 additions and 121 deletions.
2 changes: 1 addition & 1 deletion arch/s390/include/asm/pgtable.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1669,7 +1669,7 @@ static inline swp_entry_t __swp_entry(unsigned long type, unsigned long offset)
#define kern_addr_valid(addr) (1)

extern int vmem_add_mapping(unsigned long start, unsigned long size);
extern int vmem_remove_mapping(unsigned long start, unsigned long size);
extern void vmem_remove_mapping(unsigned long start, unsigned long size);
extern int s390_enable_sie(void);
extern int s390_enable_skey(void);
extern void s390_reset_cmma(struct mm_struct *mm);
Expand Down
25 changes: 13 additions & 12 deletions arch/s390/mm/extmem.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -313,15 +313,10 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
goto out_free;
}

rc = vmem_add_mapping(seg->start_addr, seg->end - seg->start_addr + 1);

if (rc)
goto out_free;

seg->res = kzalloc(sizeof(struct resource), GFP_KERNEL);
if (seg->res == NULL) {
rc = -ENOMEM;
goto out_shared;
goto out_free;
}
seg->res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
seg->res->start = seg->start_addr;
Expand All @@ -335,12 +330,17 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
if (rc == SEG_TYPE_SC ||
((rc == SEG_TYPE_SR || rc == SEG_TYPE_ER) && !do_nonshared))
seg->res->flags |= IORESOURCE_READONLY;

/* Check for overlapping resources before adding the mapping. */
if (request_resource(&iomem_resource, seg->res)) {
rc = -EBUSY;
kfree(seg->res);
goto out_shared;
goto out_free_resource;
}

rc = vmem_add_mapping(seg->start_addr, seg->end - seg->start_addr + 1);
if (rc)
goto out_resource;

if (do_nonshared)
diag_cc = dcss_diag(&loadnsr_scode, seg->dcss_name,
&start_addr, &end_addr);
Expand All @@ -351,14 +351,14 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
dcss_diag(&purgeseg_scode, seg->dcss_name,
&dummy, &dummy);
rc = diag_cc;
goto out_resource;
goto out_mapping;
}
if (diag_cc > 1) {
pr_warn("Loading DCSS %s failed with rc=%ld\n", name, end_addr);
rc = dcss_diag_translate_rc(end_addr);
dcss_diag(&purgeseg_scode, seg->dcss_name,
&dummy, &dummy);
goto out_resource;
goto out_mapping;
}
seg->start_addr = start_addr;
seg->end = end_addr;
Expand All @@ -377,11 +377,12 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long
(void*) seg->end, segtype_string[seg->vm_segtype]);
}
goto out;
out_mapping:
vmem_remove_mapping(seg->start_addr, seg->end - seg->start_addr + 1);
out_resource:
release_resource(seg->res);
out_free_resource:
kfree(seg->res);
out_shared:
vmem_remove_mapping(seg->start_addr, seg->end - seg->start_addr + 1);
out_free:
kfree(seg);
out:
Expand Down
115 changes: 7 additions & 108 deletions arch/s390/mm/vmem.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,14 +20,6 @@

static DEFINE_MUTEX(vmem_mutex);

struct memory_segment {
struct list_head list;
unsigned long start;
unsigned long size;
};

static LIST_HEAD(mem_segs);

static void __ref *vmem_alloc_pages(unsigned int order)
{
unsigned long size = PAGE_SIZE << order;
Expand Down Expand Up @@ -300,94 +292,25 @@ void vmemmap_free(unsigned long start, unsigned long end,
{
}

/*
* Add memory segment to the segment list if it doesn't overlap with
* an already present segment.
*/
static int insert_memory_segment(struct memory_segment *seg)
{
struct memory_segment *tmp;

if (seg->start + seg->size > VMEM_MAX_PHYS ||
seg->start + seg->size < seg->start)
return -ERANGE;

list_for_each_entry(tmp, &mem_segs, list) {
if (seg->start >= tmp->start + tmp->size)
continue;
if (seg->start + seg->size <= tmp->start)
continue;
return -ENOSPC;
}
list_add(&seg->list, &mem_segs);
return 0;
}

/*
* Remove memory segment from the segment list.
*/
static void remove_memory_segment(struct memory_segment *seg)
{
list_del(&seg->list);
}

static void __remove_shared_memory(struct memory_segment *seg)
void vmem_remove_mapping(unsigned long start, unsigned long size)
{
remove_memory_segment(seg);
vmem_remove_range(seg->start, seg->size);
}

int vmem_remove_mapping(unsigned long start, unsigned long size)
{
struct memory_segment *seg;
int ret;

mutex_lock(&vmem_mutex);

ret = -ENOENT;
list_for_each_entry(seg, &mem_segs, list) {
if (seg->start == start && seg->size == size)
break;
}

if (seg->start != start || seg->size != size)
goto out;

ret = 0;
__remove_shared_memory(seg);
kfree(seg);
out:
vmem_remove_range(start, size);
mutex_unlock(&vmem_mutex);
return ret;
}

int vmem_add_mapping(unsigned long start, unsigned long size)
{
struct memory_segment *seg;
int ret;

mutex_lock(&vmem_mutex);
ret = -ENOMEM;
seg = kzalloc(sizeof(*seg), GFP_KERNEL);
if (!seg)
goto out;
seg->start = start;
seg->size = size;

ret = insert_memory_segment(seg);
if (ret)
goto out_free;
if (start + size > VMEM_MAX_PHYS ||
start + size < start)
return -ERANGE;

mutex_lock(&vmem_mutex);
ret = vmem_add_mem(start, size);
if (ret)
goto out_remove;
goto out;

out_remove:
__remove_shared_memory(seg);
out_free:
kfree(seg);
out:
vmem_remove_range(start, size);
mutex_unlock(&vmem_mutex);
return ret;
}
Expand Down Expand Up @@ -421,27 +344,3 @@ void __init vmem_map_init(void)
pr_info("Write protected kernel read-only data: %luk\n",
(unsigned long)(__end_rodata - _stext) >> 10);
}

/*
* Convert memblock.memory to a memory segment list so there is a single
* list that contains all memory segments.
*/
static int __init vmem_convert_memory_chunk(void)
{
struct memblock_region *reg;
struct memory_segment *seg;

mutex_lock(&vmem_mutex);
for_each_memblock(memory, reg) {
seg = kzalloc(sizeof(*seg), GFP_KERNEL);
if (!seg)
panic("Out of memory...\n");
seg->start = reg->base;
seg->size = reg->size;
insert_memory_segment(seg);
}
mutex_unlock(&vmem_mutex);
return 0;
}

core_initcall(vmem_convert_memory_chunk);

0 comments on commit f05f62d

Please sign in to comment.