Messages in this thread Patch in this message | | | Date | Tue, 12 Mar 2019 13:09:32 -0700 | From | Jaegeuk Kim <> | Subject | Re: [PATCH] f2fs: fix to avoid deadlock in f2fs_read_inline_dir() |
| |
On 03/12, Chao Yu wrote: > As Jiqun Li reported in bugzilla: > > https://bugzilla.kernel.org/show_bug.cgi?id=202883 > > sometimes, dead lock when make system call SYS_getdents64 with fsync() is > called by another process. > > monkey running on android9.0 > > 1. task 9785 held sbi->cp_rwsem and waiting lock_page() > 2. task 10349 held mm_sem and waiting sbi->cp_rwsem > 3. task 9709 held lock_page() and waiting mm_sem > > so this is a dead lock scenario. > > task stack is show by crash tools as following > > crash_arm64> bt ffffffc03c354080 > PID: 9785 TASK: ffffffc03c354080 CPU: 1 COMMAND: "RxIoScheduler-3" > >> #7 [ffffffc01b50fac0] __lock_page at ffffff80081b11e8 > > crash-arm64> bt 10349 > PID: 10349 TASK: ffffffc018b83080 CPU: 1 COMMAND: "BUGLY_ASYNC_UPL" > >> #3 [ffffffc01f8cfa40] rwsem_down_read_failed at ffffff8008a93afc > PC: 00000033 LR: 00000000 SP: 00000000 PSTATE: ffffffffffffffff > > crash-arm64> bt 9709 > PID: 9709 TASK: ffffffc03e7f3080 CPU: 1 COMMAND: "IntentService[A" > >> #3 [ffffffc001e67850] rwsem_down_read_failed at ffffff8008a93afc > >> #8 [ffffffc001e67b80] el1_ia at ffffff8008084fc4 > PC: ffffff8008274114 [compat_filldir64+120] > LR: ffffff80083584d4 [f2fs_fill_dentries+448] > SP: ffffffc001e67b80 PSTATE: 80400145 > X29: ffffffc001e67b80 X28: 0000000000000000 X27: 000000000000001a > X26: 00000000000093d7 X25: ffffffc070d52480 X24: 0000000000000008 > X23: 0000000000000028 X22: 00000000d43dfd60 X21: ffffffc001e67e90 > X20: 0000000000000011 X19: ffffff80093a4000 X18: 0000000000000000 > X17: 0000000000000000 X16: 0000000000000000 X15: 0000000000000000 > X14: ffffffffffffffff X13: 0000000000000008 X12: 0101010101010101 > X11: 7f7f7f7f7f7f7f7f X10: 6a6a6a6a6a6a6a6a X9: 7f7f7f7f7f7f7f7f > X8: 0000000080808000 X7: ffffff800827409c X6: 0000000080808000 > X5: 0000000000000008 X4: 00000000000093d7 X3: 000000000000001a > X2: 0000000000000011 X1: ffffffc070d52480 X0: 0000000000800238 > >> #9 [ffffffc001e67be0] f2fs_fill_dentries at ffffff80083584d0 > PC: 0000003c LR: 00000000 SP: 00000000 PSTATE: 000000d9 > X12: f48a02ff X11: d4678960 X10: d43dfc00 X9: d4678ae4 > X8: 00000058 X7: d4678994 X6: d43de800 X5: 000000d9 > X4: d43dfc0c X3: d43dfc10 X2: d46799c8 X1: 00000000 > X0: 00001068 > > Below potential deadlock will happen between three threads: > Thread A Thread B Thread C > - f2fs_do_sync_file > - f2fs_write_checkpoint > - down_write(&sbi->node_change) -- 1) > - do_page_fault > - down_write(&mm->mmap_sem) -- 2) > - do_wp_page > - f2fs_vm_page_mkwrite > - getdents64 > - f2fs_read_inline_dir > - lock_page -- 3) > - f2fs_sync_node_pages > - lock_page -- 3) > - __do_map_lock > - down_read(&sbi->node_change) -- 1) > - f2fs_fill_dentries > - dir_emit > - compat_filldir64 > - do_page_fault > - down_read(&mm->mmap_sem) -- 2) > > Since f2fs_readdir is protected by inode.i_rwsem, there should not be
Well, what about other dir operations which can convert inline_dentry? How about allocating a buffer shortly like this?
--- fs/f2fs/inline.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c index a1381d05956b..50a946d55778 100644 --- a/fs/f2fs/inline.c +++ b/fs/f2fs/inline.c @@ -647,12 +647,10 @@ int f2fs_read_inline_dir(struct file *file, struct dir_context *ctx, struct inode *inode = file_inode(file); struct page *ipage = NULL; struct f2fs_dentry_ptr d; - void *inline_dentry = NULL; + void *inline_dentry = NULL, *buf = NULL; int err; - make_dentry_ptr_inline(inode, &d, inline_dentry); - - if (ctx->pos == d.max) + if (ctx->pos >= NR_INLINE_DENTRY(inode)) return 0; ipage = f2fs_get_node_page(F2FS_I_SB(inode), inode->i_ino); @@ -660,14 +658,24 @@ int f2fs_read_inline_dir(struct file *file, struct dir_context *ctx, return PTR_ERR(ipage); inline_dentry = inline_data_addr(inode, ipage); + buf = f2fs_kmalloc(F2FS_I_SB(inode), + MAX_INLINE_DATA(inode), GFP_F2FS_ZERO); + if (!buf) { + f2fs_put_page(ipage, 1); + err = -ENOMEM; + goto out; + } + memcpy(buf, inline_dentry, MAX_INLINE_DATA(inode)); + make_dentry_ptr_inline(inode, &d, buf); - make_dentry_ptr_inline(inode, &d, inline_dentry); + f2fs_put_page(ipage, 1); err = f2fs_fill_dentries(ctx, &d, 0, fstr); if (!err) ctx->pos = d.max; - f2fs_put_page(ipage, 1); + kvfree(buf); +out: return err < 0 ? err : 0; } -- 2.19.0.605.g01d371f741-goog
| |