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memobj: transform memobj lock to refcounting

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We had a deadlock between:
 - free_process_memory_range (take lock) -> ihk_mc_pt_free_range ->
... -> remote_flush_tlb_array_cpumask -> "/* Wait for all cores */"
and
 - obj_list_lookup() under fileobj_list_lock that disabled irqs
and thus never ack'd the remote flush

The rework is quite big but removes the need for the big lock,
although devobj and shmobj needed a new smaller lock to be
introduced - the new locks are used much more locally and
should not cause problems.

On the bright side, refcounting being moved to memobj level means
we could remove refcounting implemented separately in all object
types and simplifies code a bit.

Change-Id: I6bc8438a98b1d8edddc91c4ac33c11b88e097ebb
This commit is contained in:
Dominique Martinet
2018-08-07 15:40:25 +09:00
parent b51886421e
commit c25fb2aa39
10 changed files with 307 additions and 403 deletions
Download Patch File Download Diff File Expand all files Collapse all files

92
kernel/devobj.c
View File

@@ -52,16 +52,15 @@ struct devobj {
uintptr_t handle;
off_t pfn_pgoff;
uintptr_t * pfn_table;
ihk_spinlock_t pfn_table_lock;
size_t npages;
};
static memobj_release_func_t devobj_release;
static memobj_ref_func_t devobj_ref;
static memobj_free_func_t devobj_free;
static memobj_get_page_func_t devobj_get_page;
static struct memobj_ops devobj_ops = {
.release = &devobj_release,
.ref = &devobj_ref,
.free = &devobj_free,
.get_page = &devobj_get_page,
};
@@ -132,6 +131,7 @@ int devobj_create(int fd, size_t len, off_t off, struct memobj **objp, int *maxp
obj->memobj.ops = &devobj_ops;
obj->memobj.flags = MF_HAS_PAGER | MF_DEV_FILE;
obj->memobj.size = len;
ihk_atomic_set(&obj->memobj.refcnt, 1);
obj->handle = result.handle;
dkprintf("%s: path=%s\n", __FUNCTION__, result.path);
@@ -145,10 +145,9 @@ int devobj_create(int fd, size_t len, off_t off, struct memobj **objp, int *maxp
strncpy(obj->memobj.path, result.path, PATH_MAX);
}
obj->ref = 1;
obj->pfn_pgoff = off >> PAGE_SHIFT;
obj->npages = npages;
ihk_mc_spinlock_init(&obj->memobj.lock);
ihk_mc_spinlock_init(&obj->pfn_table_lock);
error = 0;
*objp = to_memobj(obj);
@@ -167,68 +166,44 @@ out:
return error;
}
static void devobj_ref(struct memobj *memobj)
static void devobj_free(struct memobj *memobj)
{
struct devobj *obj = to_devobj(memobj);
dkprintf("devobj_ref(%p %lx):\n", obj, obj->handle);
memobj_lock(&obj->memobj);
++obj->ref;
memobj_unlock(&obj->memobj);
return;
}
static void devobj_release(struct memobj *memobj)
{
struct devobj *obj = to_devobj(memobj);
struct devobj *free_obj = NULL;
uintptr_t handle;
const size_t uintptr_per_page = (PAGE_SIZE / sizeof(uintptr_t));
const size_t pfn_npages =
(obj->npages + uintptr_per_page - 1) / uintptr_per_page;
int error;
ihk_mc_user_context_t ctx;
dkprintf("devobj_release(%p %lx)\n", obj, obj->handle);
dkprintf("%s(%p %lx)\n", __func__, obj, obj->handle);
memobj_lock(&obj->memobj);
--obj->ref;
if (obj->ref <= 0) {
free_obj = obj;
}
handle = obj->handle;
memobj_unlock(&obj->memobj);
if (free_obj) {
if (!(free_obj->memobj.flags & MF_HOST_RELEASED)) {
int error;
ihk_mc_user_context_t ctx;
ihk_mc_syscall_arg0(&ctx) = PAGER_REQ_UNMAP;
ihk_mc_syscall_arg1(&ctx) = handle;
ihk_mc_syscall_arg2(&ctx) = 1;
ihk_mc_syscall_arg0(&ctx) = PAGER_REQ_UNMAP;
ihk_mc_syscall_arg1(&ctx) = handle;
ihk_mc_syscall_arg2(&ctx) = 1;
error = syscall_generic_forwarding(__NR_mmap, &ctx);
if (error) {
kprintf("devobj_release(%p %lx):"
"release failed. %d\n",
free_obj, handle, error);
/* through */
}
}
if (obj->pfn_table) {
// Don't call memory_stat_rss_sub() because devobj related pages don't reside in main memory
ihk_mc_free_pages(obj->pfn_table, pfn_npages);
}
if (to_memobj(free_obj)->path) {
kfree(to_memobj(free_obj)->path);
}
kfree(free_obj);
error = syscall_generic_forwarding(__NR_mmap, &ctx);
if (error) {
kprintf("%s(%p %lx): release failed. %d\n",
__func__, obj, handle, error);
/* through */
}
dkprintf("devobj_release(%p %lx):free %p\n",
obj, handle, free_obj);
if (obj->pfn_table) {
// Don't call memory_stat_rss_sub() because devobj related
// pages don't reside in main memory
ihk_mc_free_pages(obj->pfn_table, pfn_npages);
}
if (to_memobj(obj)->path) {
kfree(to_memobj(obj)->path);
}
kfree(obj);
dkprintf("%s(%p %lx):free\n", __func__, obj, handle);
return;
}
@@ -252,14 +227,11 @@ static int devobj_get_page(struct memobj *memobj, off_t off, int p2align, uintpt
ix = pgoff - obj->pfn_pgoff;
dkprintf("ix: %ld\n", ix);
memobj_lock(&obj->memobj);
pfn = obj->pfn_table[ix];
#ifdef PROFILE_ENABLE
profile_event_add(PROFILE_page_fault_dev_file, PAGE_SIZE);
#endif // PROFILE_ENABLE
pfn = obj->pfn_table[ix];
if (!(pfn & PFN_VALID)) {
memobj_unlock(&obj->memobj);
ihk_mc_syscall_arg0(&ctx) = PAGER_REQ_PFN;
ihk_mc_syscall_arg1(&ctx) = obj->handle;
ihk_mc_syscall_arg2(&ctx) = off & ~(PAGE_SIZE - 1);
@@ -293,11 +265,9 @@ static int devobj_get_page(struct memobj *memobj, off_t off, int p2align, uintpt
dkprintf("devobj_get_page(%p %lx,%lx,%d):PFN_PRESENT after %#lx\n", memobj, obj->handle, off, p2align, pfn);
}
memobj_lock(&obj->memobj);
obj->pfn_table[ix] = pfn;
// Don't call memory_stat_rss_add() because devobj related pages don't reside in main memory
}
memobj_unlock(&obj->memobj);
if (!(pfn & PFN_PRESENT)) {
kprintf("devobj_get_page(%p %lx,%lx,%d):not present. %lx\n", memobj, obj->handle, off, p2align, pfn);