f2fs: fix an oops in f2fs_is_compressed_page

This patch is to fix a crash: #3 [ffffb6580689f898] oops_end at ffffffffa2835bc2 #4 [ffffb6580689f8b8] no_context at ffffffffa28766e7 #5 [ffffb6580689f920] async_page_fault at ffffffffa320135e [exception RIP: f2fs_is_compressed_page+34] RIP: ffffffffa2ba83a2 RSP: ffffb6580689f9d8 RFLAGS: 00010213 RAX: 0000000000000001 RBX: fffffc0f50b34bc0 RCX: 0000000000002122 RDX: 0000000000002123 RSI: 0000000000000c00 RDI: fffffc0f50b34bc0 RBP: ffff97e815a40178 R8: 0000000000000000 R9: ffff97e83ffc9000 R10: 0000000000032300 R11: 0000000000032380 R12: ffffb6580689fa38 R13: fffffc0f50b34bc0 R14: ffff97e825cbd000 R15: 0000000000000c00 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #6 [ffffb6580689f9d8] __is_cp_guaranteed at ffffffffa2b7ea98 #7 [ffffb6580689f9f0] f2fs_submit_page_write at ffffffffa2b81a69 #8 [ffffb6580689fa30] f2fs_do_write_meta_page at ffffffffa2b99777 #9 [ffffb6580689fae0] __f2fs_write_meta_page at ffffffffa2b75f1a #10 [ffffb6580689fb18] f2fs_sync_meta_pages at ffffffffa2b77466 #11 [ffffb6580689fc98] do_checkpoint at ffffffffa2b78e46 #12 [ffffb6580689fd88] f2fs_write_checkpoint at ffffffffa2b79c29 #13 [ffffb6580689fdd0] f2fs_sync_fs at ffffffffa2b69d95 #14 [ffffb6580689fe20] sync_filesystem at ffffffffa2ad2574 #15 [ffffb6580689fe30] generic_shutdown_super at ffffffffa2a9b582 #16 [ffffb6580689fe48] kill_block_super at ffffffffa2a9b6d1 #17 [ffffb6580689fe60] kill_f2fs_super at ffffffffa2b6abe1 #18 [ffffb6580689fea0] deactivate_locked_super at ffffffffa2a9afb6 #19 [ffffb6580689feb8] cleanup_mnt at ffffffffa2abcad4 #20 [ffffb6580689fee0] task_work_run at ffffffffa28bca28 #21 [ffffb6580689ff00] exit_to_usermode_loop at ffffffffa28050b7 #22 [ffffb6580689ff38] do_syscall_64 at ffffffffa280560e #23 [ffffb6580689ff50] entry_SYSCALL_64_after_hwframe at ffffffffa320008c This occurred when umount f2fs if enable F2FS_FS_COMPRESSION with F2FS_IO_TRACE. Fixes it by adding IS_IO_TRACED_PAGE to check validity of pid for page_private. Signed-off-by: Yu Changchun <[email protected]> Reviewed-by: Chao Yu <[email protected]> Signed-off-by: Jaegeuk Kim <[email protected]>
radcolor · Jul 12, 2020 · dad4917 · dad4917
1 parent 8cd1f29
commit dad4917
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diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
@@ -55,6 +55,13 @@ bool f2fs_is_compressed_page(struct page *page)
 		return false;
 	if (IS_ATOMIC_WRITTEN_PAGE(page) || IS_DUMMY_WRITTEN_PAGE(page))
 		return false;
+	/*
+	 * page->private may be set with pid.
+	 * pid_max is enough to check if it is traced.
+	 */
+	if (IS_IO_TRACED_PAGE(page))
+		return false;
+
 	f2fs_bug_on(F2FS_M_SB(page->mapping),
 		*((u32 *)page_private(page)) != F2FS_COMPRESSED_PAGE_MAGIC);
 	return true;

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
@@ -1262,6 +1262,14 @@ enum fsync_mode {
 	FSYNC_MODE_NOBARRIER,	/* fsync behaves nobarrier based on posix */
 };
 
+#ifdef CONFIG_F2FS_IO_TRACE
+#define IS_IO_TRACED_PAGE(page)			\
+		(page_private(page) > 0 &&		\
+		 page_private(page) < (unsigned long)PID_MAX_LIMIT)
+#else
+#define IS_IO_TRACED_PAGE(page) (0)
+#endif
+
 #ifdef CONFIG_F2FS_FS_ENCRYPTION
 #define DUMMY_ENCRYPTION_ENABLED(sbi) \
 			(unlikely(F2FS_OPTION(sbi).test_dummy_encryption))