syzkaller reported a three-level circle calls (netfs_rreq_assess,
netfs_retry_reads, netfs_rreq_terminated), during an unbuffered or direct
I/O read. [1]
netfs_rreq_terminated() only checks that subreq's transferred is greater
than consumed and then sets the retry flag. There is no limit on the number
of retries, and there is no judgment on whether the retry is effective in
reading new data. This hitting the stack guard page.
To avoid the issue, let's add retry read times and the length of the data
just read in struct netfs_io_subrequest, use them to assess the state of a
read request and decide what to do retry.
[1]
BUG: TASK stack guard page was hit at ffffc9000482ff48 (stack is ffffc90004830000..ffffc90004838000)
Oops: stack guard page: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 3 UID: 0 PID: 6237 Comm: syz-executor663 Not tainted 6.12.0-rc6-syzkaller-00077-g2e1b3cc9d7f7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:mark_lock+0x25/0xc60 kernel/locking/lockdep.c:4686
Code: 90 90 90 90 90 55 48 89 e5 41 57 41 56 41 89 d6 48 ba 00 00 00 00 00 fc ff df 41 55 41 54 53 48 83 e4 f0 48 81 ec 10 01 00 00 <48> c7 44 24 30 b3 8a b5 41 48 8d 44 24 30 48 c7 44 24 38 c0 4d 7a
RSP: 0018:ffffc9000482ff50 EFLAGS: 00010086
RAX: 000000000000000c RBX: ffff8880306c2fba RCX: 0000000000000002
RDX: dffffc0000000000 RSI: ffff8880306c2f98 RDI: ffff8880306c2440
RBP: ffffc90004830088 R08: 0000000000000000 R09: 0000000000000006
R10: ffffffff96e2dd27 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8880306c2f98 R14: 0000000000000008 R15: ffff8880306c2440
FS: 00007fedf3b6e6c0(0000) GS:ffff88806a900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc9000482ff48 CR3: 000000002c910000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<#DF>
</#DF>
<TASK>
mark_usage kernel/locking/lockdep.c:4646 [inline]
__lock_acquire+0x906/0x3ce0 kernel/locking/lockdep.c:5156
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
___slab_alloc+0x123/0x1880 mm/slub.c:3695
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3908
__slab_alloc_node mm/slub.c:3961 [inline]
slab_alloc_node mm/slub.c:4122 [inline]
kmem_cache_alloc_noprof+0x2a7/0x2f0 mm/slub.c:4141
radix_tree_node_alloc.constprop.0+0x1e8/0x350 lib/radix-tree.c:253
idr_get_free+0x528/0xa40 lib/radix-tree.c:1506
idr_alloc_u32+0x191/0x2f0 lib/idr.c:46
idr_alloc+0xc1/0x130 lib/idr.c:87
p9_tag_alloc+0x394/0x870 net/9p/client.c:321
p9_client_prepare_req+0x19f/0x4d0 net/9p/client.c:644
p9_client_zc_rpc.constprop.0+0x105/0x880 net/9p/client.c:793
p9_client_read_once+0x443/0x820 net/9p/client.c:1570
p9_client_read+0x13f/0x1b0 net/9p/client.c:1534
v9fs_issue_read+0x115/0x310 fs/9p/vfs_addr.c:74
netfs_retry_read_subrequests fs/netfs/read_retry.c:60 [inline]
netfs_retry_reads+0x153a/0x1d00 fs/netfs/read_retry.c:232
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
...
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_dispatch_unbuffered_reads fs/netfs/direct_read.c:103 [inline]
netfs_unbuffered_read fs/netfs/direct_read.c:127 [inline]
netfs_unbuffered_read_iter_locked+0x12f6/0x19b0 fs/netfs/direct_read.c:221
netfs_unbuffered_read_iter+0xc5/0x100 fs/netfs/direct_read.c:256
v9fs_file_read_iter+0xbf/0x100 fs/9p/vfs_file.c:361
do_iter_readv_writev+0x614/0x7f0 fs/read_write.c:832
vfs_readv+0x4cf/0x890 fs/read_write.c:1025
do_preadv fs/read_write.c:1142 [inline]
__do_sys_preadv fs/read_write.c:1192 [inline]
__se_sys_preadv fs/read_write.c:1187 [inline]
__x64_sys_preadv+0x22d/0x310 fs/read_write.c:1187
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fedf3bd4dd9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fedf3b6e168 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007fedf3c5e318 RCX: 00007fedf3bd4dd9
RDX: 0000000000000001 RSI: 00000000200015c0 RDI: 0000000000000003
RBP: 00007fedf3c5e310 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fedf3c5e31c
R13: 000000000000000b R14: 00007fffe9d355b0 R15: 00007fffe9d35698
</TASK>
Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Reported-and-tested-by: syzbot+1fc6f64c40a9d143cfb6@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=1fc6f64c40a9d143cfb6
Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx>
---
fs/9p/vfs_addr.c | 5 ++++-
fs/netfs/buffered_read.c | 1 +
fs/netfs/direct_read.c | 1 +
fs/netfs/read_collect.c | 9 ++++++---
fs/netfs/read_retry.c | 2 ++
include/linux/netfs.h | 2 ++
6 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 819c75233235..9fcc77bc77bd 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -80,8 +80,11 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
if (pos + total >= i_size_read(rreq->inode))
__set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags);
- if (!err)
+ if (!err) {
subreq->transferred += total;
+ subreq->fresh_len = total;
+ } else
+ subreq->fresh_len = 0;
netfs_read_subreq_terminated(subreq, err, false);
}
diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index c40e226053cc..a233412ba08f 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -233,6 +233,7 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
subreq->start = start;
subreq->len = size;
+ subreq->rretry_times = 0;
atomic_inc(&rreq->nr_outstanding);
spin_lock_bh(&rreq->lock);
diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c
index b1a66a6e6bc2..beb81e06d13b 100644
--- a/fs/netfs/direct_read.c
+++ b/fs/netfs/direct_read.c
@@ -66,6 +66,7 @@ static int netfs_dispatch_unbuffered_reads(struct netfs_io_request *rreq)
subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
subreq->start = start;
subreq->len = size;
+ subreq->rretry_times = 0;
atomic_inc(&rreq->nr_outstanding);
spin_lock_bh(&rreq->lock);
diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c
index b18c65ba5580..805e8f400797 100644
--- a/fs/netfs/read_collect.c
+++ b/fs/netfs/read_collect.c
@@ -509,9 +509,12 @@ void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
} else {
trace_netfs_sreq(subreq, netfs_sreq_trace_short);
if (subreq->transferred > subreq->consumed) {
- __set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
- __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
- set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
+ /* if we didn't read new data, abandon retry*/
+ if (subreq->rretry_times && subreq->fresh_len) {
+ __set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+ set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
+ }
} else if (!__test_and_set_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags)) {
__set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c
index 0350592ea804..7aa0420cb4c4 100644
--- a/fs/netfs/read_retry.c
+++ b/fs/netfs/read_retry.c
@@ -56,6 +56,7 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
if (test_bit(NETFS_SREQ_FAILED, &subreq->flags))
break;
if (__test_and_clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {
+ subreq->rretry_times++;
netfs_reset_iter(subreq);
netfs_reissue_read(rreq, subreq);
}
@@ -183,6 +184,7 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
goto abandon;
subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
subreq->start = start;
+ subreq->rretry_times = 0;
/* We get two refs, but need just one. */
netfs_put_subrequest(subreq, false, netfs_sreq_trace_new);
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 5eaceef41e6c..c0b1f058f09a 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -191,6 +191,8 @@ struct netfs_io_subrequest {
unsigned char curr_folio_order; /* Order of folio */
struct folio_queue *curr_folioq; /* Queue segment in which current folio resides */
unsigned long flags;
+ size_t fresh_len; /* The length of the data just read */
+ u8 rretry_times; /* The times of retry read */
#define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */
#define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */
#define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
--
2.43.0
