On Tue, Apr 23, 2019 at 12:58:11PM -0400, Qian Cai wrote: > The first kmemleak_scan() after boot would trigger a crash below because > > kernel_init > free_initmem > mem_encrypt_free_decrypted_mem > free_init_pages > > unmapped some memory inside the .bss with DEBUG_PAGEALLOC=y. Since > kmemleak_init() will register the .data/.bss sections (only register > .data..ro_after_init if not within .data) and then kmemleak_scan() will > scan those address and dereference them looking for pointer referencing. > If free_init_pages() free and unmap pages in those sections, > kmemleak_scan() will trigger a crash if referencing one of those > addresses. > > BUG: unable to handle kernel paging request at ffffffffbd402000 > CPU: 12 PID: 325 Comm: kmemleak Not tainted 5.1.0-rc4+ #4 > RIP: 0010:scan_block+0x58/0x160 > Call Trace: > scan_gray_list+0x1d9/0x280 > kmemleak_scan+0x485/0xad0 > kmemleak_scan_thread+0x9f/0xc4 > kthread+0x1d2/0x1f0 > ret_from_fork+0x35/0x40 > > Since kmemleak_free_part() is tolerant to unknown objects (not tracked by > kmemleak), it is fine to call it from free_init_pages() even if not all > address ranges passed to this function are known to kmemleak. > > Signed-off-by: Qian Cai <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
