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AJvYcCVS9AFeDCu69Lju4xNXpUsywBq3hYq/kq89MgAezhd0r01zrqYrm+TIjpkf53mo45gNpf4a5rS92qGDy+k=@vger.kernel.org X-Gm-Message-State: AOJu0YzkBy72ZGGvKF6wNkvqWKtAjHGP9WEvl1l9yC2WwvUPiCqUiitV L/zaeqFyHcn0k5XlVFHOyY6aC0ilMjsGlOsUM6PhmKa0Is4H7lgDkmLmfGjYAizoGb6CLzWpnsh 2fjnjfYRTCeRTBP+Xy/82rNTVlrs= X-Gm-Gg: ASbGncuzgCfWLJE+V7B5SnibHZPeWteSt6DKmOkNUn18z2nF609MPs3FteomTYZcIL2 lW+cl5fPzYztzspuDkm8aAjd18CSXzPMT X-Google-Smtp-Source: AGHT+IFjiOOM8DcxBdrMs87n9NgH8sqqh/pm3JJandQSt+FxrhXgNaZKIkSsT5feYP/NgF2wE9+RyhKCd2efRxn5A1Q= X-Received: by 2002:a05:6000:2a1:b0:37d:2e83:bc44 with SMTP id ffacd0b85a97d-38254b270femr553841f8f.9.1732094356576; Wed, 20 Nov 2024 01:19:16 -0800 (PST) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241112110627.1314632-1-xiuhong.wang@unisoc.com> <5b0c17da-f1e1-490d-a560-3312bc8c3247@kernel.org> <65b89566-1038-4422-9e2e-4d7da26dd1c7@kernel.org> <5b40ca3c-efd6-4b50-8d11-845930a0e365@kernel.org> In-Reply-To: <5b40ca3c-efd6-4b50-8d11-845930a0e365@kernel.org> From: Zhiguo Niu Date: Wed, 20 Nov 2024 17:19:05 +0800 Message-ID: Subject: Re: [PATCH] f2fs: Fix to avoid long time to shrink extent cache To: Chao Yu Cc: Xiuhong Wang , Xiuhong Wang , jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, hao_hao.wang@unisoc.com, ke.wang@unisoc.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Chao Yu =E4=BA=8E2024=E5=B9=B411=E6=9C=8820=E6=97=A5=E5= =91=A8=E4=B8=89 16:15=E5=86=99=E9=81=93=EF=BC=9A > > On 2024/11/20 13:45, Zhiguo Niu wrote: > > Chao Yu =E4=BA=8E2024=E5=B9=B411=E6=9C=8820=E6=97=A5= =E5=91=A8=E4=B8=89 11:26=E5=86=99=E9=81=93=EF=BC=9A > >> > >> On 2024/11/19 16:26, Zhiguo Niu wrote: > >>> Chao Yu =E4=BA=8E2024=E5=B9=B411=E6=9C=8819=E6=97= =A5=E5=91=A8=E4=BA=8C 15:50=E5=86=99=E9=81=93=EF=BC=9A > >>>> > >>>> On 2024/11/19 14:46, Xiuhong Wang wrote: > >>>>> Chao Yu =E4=BA=8E2024=E5=B9=B411=E6=9C=8819=E6=97= =A5=E5=91=A8=E4=BA=8C 14:05=E5=86=99=E9=81=93=EF=BC=9A > >>>>>> > >>>>>> On 2024/11/12 19:06, Xiuhong Wang wrote: > >>>>>>> We encountered a system hang problem based on the following > >>>>>>> experiment: > >>>>>>> There are 17 processes, 8 of which do 4k data read, write and > >>>>>>> compare tests, and 8 do 64k read, write and compare tests. Each > >>>>>>> thread writes a 256M file, and another thread writes a large file > >>>>>>> to 80% of the disk, and then keeps doing read operations, all of > >>>>>>> which are direct operations. This will cause the large file to be > >>>>>>> filled to 80% of the disk to be severely fragmented. On a 512GB > >>>>>>> device, this large file may generate a huge zombie extent tree. > >>>>>>> > >>>>>>> When system shutting down, the init process needs to wait for the > >>>>>>> writeback process, and the writeback process may encounter the > >>>>>>> situation where the READ_EXTENT_CACHE space is insufficient and > >>>>>>> needs to free the zombie extent tree. The extent tree has a large > >>>>>>> number of extent nodes, it will a long free time to free, which > >>>>>>> triggers system hang. > >>>>>> > > The stack when the problem occurs is as follows: > >>>>>>> crash_arm64> bt 1 > >>>>>>> PID: 1 TASK: ffffff80801a9200 CPU: 1 COMMAND: "init" > >>>>>>> #0 [ffffffc00806b9a0] __switch_to at ffffffc00810711c > >>>>>>> #1 [ffffffc00806ba00] __schedule at ffffffc0097c1c4c > >>>>>>> #2 [ffffffc00806ba60] schedule at ffffffc0097c2308 > >>>>>>> #3 [ffffffc00806bab0] wb_wait_for_completion at ffffffc00863= 20d4 > >>>>>>> #4 [ffffffc00806bb20] writeback_inodes_sb at ffffffc00863719= c > >>>>>>> #5 [ffffffc00806bba0] sync_filesystem at ffffffc00863c98c > >>>>>>> #6 [ffffffc00806bbc0] f2fs_quota_off_umount at ffffffc00886f= c60 > >>>>>>> #7 [ffffffc00806bc20] f2fs_put_super at ffffffc0088715b4 > >>>>>>> #8 [ffffffc00806bc60] generic_shutdown_super at ffffffc0085c= d61c > >>>>>>> #9 [ffffffc00806bcd0] kill_f2fs_super at ffffffc00886b3dc > >>>>>>> > >>>>>>> crash_arm64> bt 14997 > >>>>>>> PID: 14997 TASK: ffffff8119d82400 CPU: 3 COMMAND: "kworker= /u16:0" > >>>>>>> #0 [ffffffc019f8b760] __detach_extent_node at ffffffc0088d5a= 58 > >>>>>>> #1 [ffffffc019f8b790] __release_extent_node at ffffffc0088d5= 970 > >>>>>>> #2 [ffffffc019f8b810] f2fs_shrink_extent_tree at ffffffc0088= d5c7c > >>>>>>> #3 [ffffffc019f8b8a0] f2fs_balance_fs_bg at ffffffc0088c109c > >>>>>>> #4 [ffffffc019f8b910] f2fs_write_node_pages at ffffffc0088bd= 4d8 > >>>>>>> #5 [ffffffc019f8b990] do_writepages at ffffffc0084a0b5c > >>>>>>> #6 [ffffffc019f8b9f0] __writeback_single_inode at ffffffc008= 62ee28 > >>>>>>> #7 [ffffffc019f8bb30] writeback_sb_inodes at ffffffc0086358c= 0 > >>>>>>> #8 [ffffffc019f8bc10] wb_writeback at ffffffc0086362dc > >>>>>>> #9 [ffffffc019f8bcc0] wb_do_writeback at ffffffc008634910 > >>>>>>> > >>>>>>> Process 14997 ran for too long and caused the system hang. > >>>>>>> > >>>>>>> At this time, there are still 1086911 extent nodes in this zombie > >>>>>>> extent tree that need to be cleaned up. > >>>>>>> > >>>>>>> crash_arm64_sprd_v8.0.3++> extent_tree.node_cnt ffffff80896cc500 > >>>>>>> node_cnt =3D { > >>>>>>> counter =3D 1086911 > >>>>>>> }, > >>>>>>> > >>>>>>> The root cause of this problem is that when the f2fs_balance_fs > >>>>>>> function is called in the write process, it will determine > >>>>>>> whether to call f2fs_balance_fs_bg, but it is difficult to > >>>>>>> meet the condition of excess_cached_nats. When the > >>>>>>> f2fs_shrink_extent_tree function is called to free during > >>>>>>> f2fs_write_node_pages, there are too many extent nodes on the > >>>>>>> extent tree, which causes a loop and causes a system hang. > >>>>>>> > >>>>>>> To solve this problem, when calling f2fs_balance_fs, check whethe= r > >>>>>>> the extent cache is sufficient. If not, release the zombie extent > >>>>>>> tree. > >>>>>>> > >>>>>>> Signed-off-by: Xiuhong Wang > >>>>>>> Signed-off-by: Zhiguo Niu > >>>>>>> --- > >>>>>>> Test the problem with the temporary versions: > >>>>>>> patch did not reproduce the problem, the patch is as follows: > >>>>>>> @@ -415,7 +415,7 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi= , bool need) > >>>>>>> f2fs_stop_checkpoint(sbi, false, STOP_CP_REAS= ON_FAULT_INJECT); > >>>>>>> > >>>>>>> /* balance_fs_bg is able to be pending */ > >>>>>>> - if (need && excess_cached_nats(sbi)) > >>>>>>> + if (need) > >>>>>>> f2fs_balance_fs_bg(sbi, false); > >>>>>>> > >>>>>>> --- > >>>>>>> fs/f2fs/segment.c | 4 +++- > >>>>>>> 1 file changed, 3 insertions(+), 1 deletion(-) > >>>>>>> > >>>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > >>>>>>> index 1766254279d2..390bec177567 100644 > >>>>>>> --- a/fs/f2fs/segment.c > >>>>>>> +++ b/fs/f2fs/segment.c > >>>>>>> @@ -415,7 +415,9 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi= , bool need) > >>>>>>> f2fs_stop_checkpoint(sbi, false, STOP_CP_REASON_= FAULT_INJECT); > >>>>>>> > >>>>>>> /* balance_fs_bg is able to be pending */ > >>>>>>> - if (need && excess_cached_nats(sbi)) > >>>>>>> + if (need && (excess_cached_nats(sbi) || > >>>>>>> + !f2fs_available_free_memory(sbi, READ_EXTEN= T_CACHE) || > >>>>>>> + !f2fs_available_free_memory(sbi, AGE_EXTENT= _CACHE))) > >>>>>> > >>>>>> Hi, > >>>>>> > >>>>>> I doubt if there is no enough memory, we may still run into > >>>>>> f2fs_shrink_extent_tree() and suffer such long time delay. > >>>>>> > >>>>>> So, can we just let __free_extent_tree() break the loop once we ha= ve > >>>>>> released entries w/ target number? something like this: > >>>>>> > >>>>>> --- > >>>>>> fs/f2fs/extent_cache.c | 15 ++++++++++----- > >>>>>> 1 file changed, 10 insertions(+), 5 deletions(-) > >>>>>> > >>>>>> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c > >>>>>> index 019c1f7b7fa5..38c71c1c4fb7 100644 > >>>>>> --- a/fs/f2fs/extent_cache.c > >>>>>> +++ b/fs/f2fs/extent_cache.c > >>>>>> @@ -379,11 +379,12 @@ static struct extent_tree *__grab_extent_tre= e(struct inode *inode, > >>>>>> } > >>>>>> > >>>>>> static unsigned int __free_extent_tree(struct f2fs_sb_info *s= bi, > >>>>>> - struct extent_tree *et) > >>>>>> + struct extent_tree *et, unsigned i= nt nr_shrink) > >>>>>> { > >>>>>> struct rb_node *node, *next; > >>>>>> struct extent_node *en; > >>>>>> unsigned int count =3D atomic_read(&et->node_cnt); > >>>>>> + unsigned int i =3D 0; > >>>>>> > >>>>>> node =3D rb_first_cached(&et->root); > >>>>>> while (node) { > >>>>>> @@ -391,6 +392,9 @@ static unsigned int __free_extent_tree(struct = f2fs_sb_info *sbi, > >>>>>> en =3D rb_entry(node, struct extent_node, rb_no= de); > >>>>>> __release_extent_node(sbi, et, en); > >>>>>> node =3D next; > >>>>>> + > >>>>>> + if (nr_shrink && ++i >=3D nr_shrink) > >>>>>> + break; > >>>>>> } > >>>>>> > >>>>>> return count - atomic_read(&et->node_cnt); > >>>>>> @@ -761,7 +765,7 @@ static void __update_extent_tree_range(struct = inode *inode, > >>>>>> } > >>>>>> > >>>>>> if (is_inode_flag_set(inode, FI_NO_EXTENT)) > >>>>>> - __free_extent_tree(sbi, et); > >>>>>> + __free_extent_tree(sbi, et, 0); > >>>>>> > >>>>>> if (et->largest_updated) { > >>>>>> et->largest_updated =3D false; > >>>>>> @@ -942,7 +946,8 @@ static unsigned int __shrink_extent_tree(struc= t f2fs_sb_info *sbi, int nr_shrink > >>>>>> list_for_each_entry_safe(et, next, &eti->zombie_list, l= ist) { > >>>>>> if (atomic_read(&et->node_cnt)) { > >>>>>> write_lock(&et->lock); > >>>>>> - node_cnt +=3D __free_extent_tree(sbi, et); > >>>>>> + node_cnt +=3D __free_extent_tree(sbi, et, > >>>>>> + nr_shrink - node_cnt - tre= e_cnt); > >>>>>> write_unlock(&et->lock); > >>>>>> } > >>>>>> f2fs_bug_on(sbi, atomic_read(&et->node_cnt)); > >>>>>> @@ -1095,7 +1100,7 @@ static unsigned int __destroy_extent_node(st= ruct inode *inode, > >>>>>> return 0; > >>>>>> > >>>>>> write_lock(&et->lock); > >>>>>> - node_cnt =3D __free_extent_tree(sbi, et); > >>>>>> + node_cnt =3D __free_extent_tree(sbi, et, 0); > >>>>>> write_unlock(&et->lock); > >>>>>> > >>>>>> return node_cnt; > >>>>>> @@ -1117,7 +1122,7 @@ static void __drop_extent_tree(struct inode = *inode, enum extent_type type) > >>>>>> return; > >>>>>> > >>>>>> write_lock(&et->lock); > >>>>>> - __free_extent_tree(sbi, et); > >>>>>> + __free_extent_tree(sbi, et, 0); > >>>>>> if (type =3D=3D EX_READ) { > >>>>>> set_inode_flag(inode, FI_NO_EXTENT); > >>>>>> if (et->largest.len) { > >>>>>> -- > >>>>>> 2.40.1 > >>>>>> > >>>>>> Thanks, > >>>>>> > >>>>>>> f2fs_balance_fs_bg(sbi, false); > >>>>>>> > >>>>>>> if (!f2fs_is_checkpoint_ready(sbi)) > >>>>>> > >>>>> > >>>>> > >>>>> Hi chao, > >>>>> > >>>>> We have also considered this approach, but the problem still occurs > >>>>> after retesting. > >>>>> 1. The problem still occurs in the following call of the unmount da= ta process. > >>>>> f2fs_put_super -> f2fs_leave_shrinker > >>>> > >>>> Yes, I guess we need to fix this path as well, however, your patch d= idn't > >>>> cover this path as well, am I missing something? > >>> Dear Chao, > >>> This patch version aim to shrink extent cache as early as possible o= n > >>> the "all write path" > >>> by "write action" -> f2fs_balance_fs -> f2fs_balance_fs_bg > >> > >> Zhiguo, thanks for explaining again. > >> > > Dear Chao, > >> However, I doubt covering all write paths is not enough, because exten= t > >> node can increase when f2fs_precache_extents() was called from paths > >> including fadvise/fiemap/swapon/ioc_precache_extents, and there may be > >> no writeback, so we may get no chance to call into f2fs_balance_fs_bg(= ), > >> e.g. there is no data update in mountpoint, or mountpoint is readonly. > > yes, Indeed it is. > >> > >>> As the comment , the "excess_cached_nats" is difficult to achieve in > >>> this scenario, and > >> > >> Another concern is, in high-end products w/ more memory, it may has le= ss > >> chance to hit newly added condition in f2fs_balance_fs()? not sure tho= ugh. > > I also agree with this. > > There is no other better idea for me(^^) excpetion for the two methods > > we discussed above. > > any good suggestions ? ^^ > Dear Chao, It is good solution to limit the maximum extent count of each inode. > What do you think of this? > > From 8646c28027d5b050938335066ab56abbeca799e7 Mon Sep 17 00:00:00 2001 > From: Chao Yu > Date: Tue, 19 Nov 2024 11:53:09 +0800 > Subject: [PATCH 1/2] f2fs: fix to shrink read extent node in batches > > Signed-off-by: Chao Yu > --- > fs/f2fs/extent_cache.c | 64 ++++++++++++++++++++++++------------------ > 1 file changed, 37 insertions(+), 27 deletions(-) > > diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c > index 019c1f7b7fa5..0c0d05f8551a 100644 > --- a/fs/f2fs/extent_cache.c > +++ b/fs/f2fs/extent_cache.c > @@ -379,21 +379,22 @@ static struct extent_tree *__grab_extent_tree(struc= t inode *inode, > } > > static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi, > - struct extent_tree *et) > + struct extent_tree *et, unsigned int nr_s= hrink) > { > struct rb_node *node, *next; > struct extent_node *en; > - unsigned int count =3D atomic_read(&et->node_cnt); > + unsigned int count; > > node =3D rb_first_cached(&et->root); > - while (node) { > + > + for (count =3D 0; node && count < nr_shrink; count++) { > next =3D rb_next(node); > en =3D rb_entry(node, struct extent_node, rb_node); > __release_extent_node(sbi, et, en); > node =3D next; > } > > - return count - atomic_read(&et->node_cnt); > + return count; > } > > static void __drop_largest_extent(struct extent_tree *et, > @@ -622,6 +623,30 @@ static struct extent_node *__insert_extent_tree(stru= ct f2fs_sb_info *sbi, > return en; > } > > +static unsigned int __destroy_extent_node(struct inode *inode, > + enum extent_type type) > +{ > + struct f2fs_sb_info *sbi =3D F2FS_I_SB(inode); > + struct extent_tree *et =3D F2FS_I(inode)->extent_tree[type]; > + unsigned int nr_shrink =3D type =3D=3D EX_READ ? > + READ_EXTENT_CACHE_SHRINK_NUMBER : > + AGE_EXTENT_CACHE_SHRINK_NUMBER; > + unsigned int node_cnt =3D 0; > + > + if (!et || !atomic_read(&et->node_cnt)) > + return 0; > + > + while (atomic_read(&et->node_cnt)) { > + write_lock(&et->lock); > + node_cnt =3D __free_extent_tree(sbi, et, nr_shrink); should be: node_cnt +=3D __free_extent_tree(sbi, et, nr_shrink); ?? > + write_unlock(&et->lock); > + } > + > + f2fs_bug_on(sbi, atomic_read(&et->node_cnt)); > + > + return node_cnt; > +} > + > static void __update_extent_tree_range(struct inode *inode, > struct extent_info *tei, enum extent_type type) > { > @@ -760,9 +785,6 @@ static void __update_extent_tree_range(struct inode *= inode, > } > } > > - if (is_inode_flag_set(inode, FI_NO_EXTENT)) > - __free_extent_tree(sbi, et); > - > if (et->largest_updated) { > et->largest_updated =3D false; > updated =3D true; > @@ -780,6 +802,9 @@ static void __update_extent_tree_range(struct inode *= inode, > out_read_extent_cache: > write_unlock(&et->lock); > > + if (is_inode_flag_set(inode, FI_NO_EXTENT)) > + __destroy_extent_node(inode, EX_READ); > + > if (updated) > f2fs_mark_inode_dirty_sync(inode, true); > } > @@ -942,7 +967,8 @@ static unsigned int __shrink_extent_tree(struct f2fs_= sb_info *sbi, int nr_shrink > list_for_each_entry_safe(et, next, &eti->zombie_list, list) { > if (atomic_read(&et->node_cnt)) { > write_lock(&et->lock); > - node_cnt +=3D __free_extent_tree(sbi, et); > + node_cnt +=3D __free_extent_tree(sbi, et, > + nr_shrink - node_cnt - tree_cnt); > write_unlock(&et->lock); > } > f2fs_bug_on(sbi, atomic_read(&et->node_cnt)); this f2fs_bug_on statment should be removed or omited? and the following free tree action can not be do if atomic_read(&et->node_cnt) !=3D0 ? thanks! > @@ -1084,23 +1110,6 @@ unsigned int f2fs_shrink_age_extent_tree(struct f2= fs_sb_info *sbi, int nr_shrink > return __shrink_extent_tree(sbi, nr_shrink, EX_BLOCK_AGE); > } > > -static unsigned int __destroy_extent_node(struct inode *inode, > - enum extent_type type) > -{ > - struct f2fs_sb_info *sbi =3D F2FS_I_SB(inode); > - struct extent_tree *et =3D F2FS_I(inode)->extent_tree[type]; > - unsigned int node_cnt =3D 0; > - > - if (!et || !atomic_read(&et->node_cnt)) > - return 0; > - > - write_lock(&et->lock); > - node_cnt =3D __free_extent_tree(sbi, et); > - write_unlock(&et->lock); > - > - return node_cnt; > -} > - > void f2fs_destroy_extent_node(struct inode *inode) > { > __destroy_extent_node(inode, EX_READ); > @@ -1109,7 +1118,6 @@ void f2fs_destroy_extent_node(struct inode *inode) > > static void __drop_extent_tree(struct inode *inode, enum extent_type ty= pe) > { > - struct f2fs_sb_info *sbi =3D F2FS_I_SB(inode); > struct extent_tree *et =3D F2FS_I(inode)->extent_tree[type]; > bool updated =3D false; > > @@ -1117,7 +1125,6 @@ static void __drop_extent_tree(struct inode *inode,= enum extent_type type) > return; > > write_lock(&et->lock); > - __free_extent_tree(sbi, et); > if (type =3D=3D EX_READ) { > set_inode_flag(inode, FI_NO_EXTENT); > if (et->largest.len) { > @@ -1126,6 +1133,9 @@ static void __drop_extent_tree(struct inode *inode,= enum extent_type type) > } > } > write_unlock(&et->lock); > + > + __destroy_extent_node(inode, type); > + > if (updated) > f2fs_mark_inode_dirty_sync(inode, true); > } > -- > 2.40.1 > > From 3a1b7ec606d6211b2eaf72d148ebe52d38a0bf59 Mon Sep 17 00:00:00 2001 > From: Chao Yu > Date: Wed, 20 Nov 2024 15:37:22 +0800 > Subject: [PATCH 2/2] f2fs: add a sysfs node to limit max read extent coun= t > per-inode > > Signed-off-by: Chao Yu > --- > Documentation/ABI/testing/sysfs-fs-f2fs | 6 ++++++ > fs/f2fs/extent_cache.c | 5 ++++- > fs/f2fs/f2fs.h | 4 ++++ > fs/f2fs/sysfs.c | 7 +++++++ > 4 files changed, 21 insertions(+), 1 deletion(-) > > diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/= testing/sysfs-fs-f2fs > index 513296bb6f29..3e1630c70d8a 100644 > --- a/Documentation/ABI/testing/sysfs-fs-f2fs > +++ b/Documentation/ABI/testing/sysfs-fs-f2fs > @@ -822,3 +822,9 @@ Description: It controls the valid block ratio= threshold not to trigger excessiv > for zoned deivces. The initial value of it is 95(%). F2FS= will stop the > background GC thread from intiating GC for sections havin= g valid blocks > exceeding the ratio. > + > +What: /sys/fs/f2fs//max_read_extent_count > +Date: November 2024 > +Contact: "Chao Yu" > +Description: It controls max read extent count for per-inode, the valu= e of threshold > + is 10240 by default. > diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c > index 0c0d05f8551a..b08563ad010d 100644 > --- a/fs/f2fs/extent_cache.c > +++ b/fs/f2fs/extent_cache.c > @@ -717,7 +717,9 @@ static void __update_extent_tree_range(struct inode *= inode, > } > > if (end < org_end && (type !=3D EX_READ || > - org_end - end >=3D F2FS_MIN_EXTENT_LEN)) = { > + (org_end - end >=3D F2FS_MIN_EXTENT_LEN && > + atomic_read(&et->node_cnt) < > + sbi->max_read_extent_count))) { > if (parts) { > __set_extent_info(&ei, > end, org_end - end, > @@ -1209,6 +1211,7 @@ void f2fs_init_extent_cache_info(struct f2fs_sb_inf= o *sbi) > sbi->hot_data_age_threshold =3D DEF_HOT_DATA_AGE_THRESHOLD; > sbi->warm_data_age_threshold =3D DEF_WARM_DATA_AGE_THRESHOLD; > sbi->last_age_weight =3D LAST_AGE_WEIGHT; > + sbi->max_read_extent_count =3D DEF_MAX_READ_EXTENT_COUNT; > } > > int __init f2fs_create_extent_cache(void) > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index b65b023a588a..6f2cbf4c5740 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -635,6 +635,9 @@ enum { > #define DEF_HOT_DATA_AGE_THRESHOLD 262144 > #define DEF_WARM_DATA_AGE_THRESHOLD 2621440 > > +/* default max read extent count per inode */ > +#define DEF_MAX_READ_EXTENT_COUNT 10240 > + > /* extent cache type */ > enum extent_type { > EX_READ, > @@ -1619,6 +1622,7 @@ struct f2fs_sb_info { > /* for extent tree cache */ > struct extent_tree_info extent_tree[NR_EXTENT_CACHES]; > atomic64_t allocated_data_blocks; /* for block age extent_c= ache */ > + unsigned int max_read_extent_count; /* max read extent count = per inode */ > > /* The threshold used for hot and warm data seperation*/ > unsigned int hot_data_age_threshold; > diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c > index bdbf24db667b..d1356c656cac 100644 > --- a/fs/f2fs/sysfs.c > +++ b/fs/f2fs/sysfs.c > @@ -787,6 +787,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a, > return count; > } > > + if (!strcmp(a->attr.name, "max_read_extent_count")) { > + if (t > UINT_MAX) > + return -EINVAL; > + *ui =3D (unsigned int)t; > + return count; > + } > + > if (!strcmp(a->attr.name, "ipu_policy")) { > if (t >=3D BIT(F2FS_IPU_MAX)) > return -EINVAL; > -- > 2.40.1 > > > > > thanks=EF=BC=81 > >> > >> + if (need && (excess_cached_nats(sbi) || > >> + !f2fs_available_free_memory(sbi, READ_EXTENT_CAC= HE) || > >> + !f2fs_available_free_memory(sbi, AGE_EXTENT_CACH= E))) > >> > >> I mean will f2fs_available_free_memory(sbi, {READ,AGE}_EXTENT_CACHE) > >> return true if available memory is sufficient? > >> > >> Thanks, > >> > >>> trigger the issue in path f2fs_write_node_pages->f2fs_balance_fs_bg(i= s > >>> called directly here). > >>> At that time, there were already a lot of extent node cnt. > >>> Thanks! > >>>> > >>>>> 2. Writing back the inode in the normal write-back process will > >>>>> release the extent cache, and the problem still occurs. The stack i= s > >>>>> as follows: > >>>> > >>>> Ditto, > >>>> > >>>> Thanks, > >>>> > >>>>> [H 103098.974356] c2 [] (rb_erase+0x204/0x334) > >>>>> [H 103098.974389] c2 [] (__release_extent_node+0x= c8/0x168) > >>>>> [H 103098.974425] c2 [] > >>>>> (f2fs_update_extent_tree_range+0x4a0/0x724) > >>>>> [H 103098.974459] c2 [] (f2fs_update_extent_cache= +0x19c/0x1b0) > >>>>> [H 103098.974495] c2 [] (f2fs_outplace_write_data= +0x74/0xf0) > >>>>> [H 103098.974525] c2 [] (f2fs_do_write_data_page+= 0x3e4/0x6c8) > >>>>> [H 103098.974552] c2 [] > >>>>> (f2fs_write_single_data_page+0x478/0xab0) > >>>>> [H 103098.974574] c2 [] (f2fs_write_cache_pages+0= x454/0xaac) > >>>>> [H 103098.974596] c2 [] (__f2fs_write_data_pages+= 0x40c/0x4f0) > >>>>> [H 103098.974617] c2 [] (f2fs_write_data_pages+0x= 30/0x40) > >>>>> [H 103098.974645] c2 [] (do_writepages+0x18c/0x3e= 8) > >>>>> [H 103098.974678] c2 [] (__writeback_single_inode= +0x48/0x498) > >>>>> [H 103098.974720] c2 [] (writeback_sb_inodes+0x45= 4/0x9b0) > >>>>> [H 103098.974754] c2 [] (__writeback_inodes_wb+0x= 198/0x224) > >>>>> [H 103098.974788] c2 [] (wb_writeback+0x1c0/0x698= ) > >>>>> [H 103098.974819] c2 [] (wb_do_writeback+0x420/0x= 54c) > >>>>> [H 103098.974853] c2 [] (wb_workfn+0xe4/0x388) > >>>> > >> >