mm/vmalloc: fix vmalloc which may return null if called with __GFP_NOFAIL

commit a421ef3 ("mm: allow !GFP_KERNEL allocations for kvmalloc")
includes support for __GFP_NOFAIL, but it presents a conflict with commit
dd54414 ("vmalloc: back off when the current task is OOM-killed").  A
possible scenario is as follows:

process-a
__vmalloc_node_range(GFP_KERNEL | __GFP_NOFAIL)
    __vmalloc_area_node()
        vm_area_alloc_pages()
		--> oom-killer send SIGKILL to process-a
        if (fatal_signal_pending(current)) break;
--> return NULL;

To fix this, do not check fatal_signal_pending() in vm_area_alloc_pages()
if __GFP_NOFAIL set.

This issue occurred during OPLUS KASAN TEST. Below is part of the log
-> oom-killer sends signal to process
[65731.222840] [ T1308] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/apps/uid_10198,task=gs.intelligence,pid=32454,uid=10198

[65731.259685] [T32454] Call trace:
[65731.259698] [T32454]  dump_backtrace+0xf4/0x118
[65731.259734] [T32454]  show_stack+0x18/0x24
[65731.259756] [T32454]  dump_stack_lvl+0x60/0x7c
[65731.259781] [T32454]  dump_stack+0x18/0x38
[65731.259800] [T32454]  mrdump_common_die+0x250/0x39c [mrdump]
[65731.259936] [T32454]  ipanic_die+0x20/0x34 [mrdump]
[65731.260019] [T32454]  atomic_notifier_call_chain+0xb4/0xfc
[65731.260047] [T32454]  notify_die+0x114/0x198
[65731.260073] [T32454]  die+0xf4/0x5b4
[65731.260098] [T32454]  die_kernel_fault+0x80/0x98
[65731.260124] [T32454]  __do_kernel_fault+0x160/0x2a8
[65731.260146] [T32454]  do_bad_area+0x68/0x148
[65731.260174] [T32454]  do_mem_abort+0x151c/0x1b34
[65731.260204] [T32454]  el1_abort+0x3c/0x5c
[65731.260227] [T32454]  el1h_64_sync_handler+0x54/0x90
[65731.260248] [T32454]  el1h_64_sync+0x68/0x6c

[65731.260269] [T32454]  z_erofs_decompress_queue+0x7f0/0x2258
--> be->decompressed_pages = kvcalloc(be->nr_pages, sizeof(struct page *), GFP_KERNEL | __GFP_NOFAIL);
	kernel panic by NULL pointer dereference.
	erofs assume kvmalloc with __GFP_NOFAIL never return NULL.
[65731.260293] [T32454]  z_erofs_runqueue+0xf30/0x104c
[65731.260314] [T32454]  z_erofs_readahead+0x4f0/0x968
[65731.260339] [T32454]  read_pages+0x170/0xadc
[65731.260364] [T32454]  page_cache_ra_unbounded+0x874/0xf30
[65731.260388] [T32454]  page_cache_ra_order+0x24c/0x714
[65731.260411] [T32454]  filemap_fault+0xbf0/0x1a74
[65731.260437] [T32454]  __do_fault+0xd0/0x33c
[65731.260462] [T32454]  handle_mm_fault+0xf74/0x3fe0
[65731.260486] [T32454]  do_mem_abort+0x54c/0x1b34
[65731.260509] [T32454]  el0_da+0x44/0x94
[65731.260531] [T32454]  el0t_64_sync_handler+0x98/0xb4
[65731.260553] [T32454]  el0t_64_sync+0x198/0x19c

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 9376130 ("mm/vmalloc: add support for __GFP_NOFAIL")
Signed-off-by: Hailong.Liu <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Suggested-by: Barry Song <[email protected]>
Reported-by: Oven <[email protected]>
Reviewed-by: Barry Song <[email protected]>
Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: hailong-liu

mm/vmalloc.c

@@ -3498,7 +3498,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
 {
 	unsigned int nr_allocated = 0;
 	gfp_t alloc_gfp = gfp;
-	bool nofail = false;
+	bool nofail = gfp & __GFP_NOFAIL;
 	struct page *page;
 	int i;
 
@@ -3555,12 +3555,11 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
 		 * and compaction etc.
 		 */
 		alloc_gfp &= ~__GFP_NOFAIL;
-		nofail = true;
 	}
 
 	/* High-order pages or fallback path if "bulk" fails. */
 	while (nr_allocated < nr_pages) {
-		if (fatal_signal_pending(current))
+		if (!nofail && fatal_signal_pending(current))
 			break;
 
 		if (nid == NUMA_NO_NODE)