| Message ID | 1531413965-5401-5-git-send-email-longman@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Waiman,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.18-rc4]
[cannot apply to next-20180713]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Waiman-Long/fs-dcache-Track-report-number-of-negative-dentries/20180714-161258
config: i386-tinyconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
:::::: branch date: 45 minutes ago
:::::: commit date: 45 minutes ago
Note: the linux-review/Waiman-Long/fs-dcache-Track-report-number-of-negative-dentries/20180714-161258 HEAD ca68ee513a450445b269248c2859302c8931a294 builds fine.
It only hurts bisectibility.
All errors (new ones prefixed by >>):
fs/dcache.c: In function 'neg_dentry_inc_slowpath':
>> fs/dcache.c:355:8: error: implicit declaration of function 'get_nr_dentry_neg'; did you mean 'neg_dentry_dec'? [-Werror=implicit-function-declaration]
cnt = get_nr_dentry_neg();
^~~~~~~~~~~~~~~~~
neg_dentry_dec
cc1: some warnings being treated as errors
# https://github.com/0day-ci/linux/commit/2aa8bf4658af0dbc07ae9ea07d04937a347e3ef4
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 2aa8bf4658af0dbc07ae9ea07d04937a347e3ef4
vim +355 fs/dcache.c
bcc9ba8b Waiman Long 2018-07-12 310
bcc9ba8b Waiman Long 2018-07-12 311 static noinline void neg_dentry_inc_slowpath(struct dentry *dentry)
bcc9ba8b Waiman Long 2018-07-12 312 {
bcc9ba8b Waiman Long 2018-07-12 313 long cnt = 0, *pcnt;
2aa8bf46 Waiman Long 2018-07-12 314 unsigned long current_time;
bcc9ba8b Waiman Long 2018-07-12 315
bcc9ba8b Waiman Long 2018-07-12 316 /*
bcc9ba8b Waiman Long 2018-07-12 317 * Try to move some negative dentry quota from the global free
bcc9ba8b Waiman Long 2018-07-12 318 * pool to the percpu count to allow more negative dentries to
bcc9ba8b Waiman Long 2018-07-12 319 * be added to the LRU.
bcc9ba8b Waiman Long 2018-07-12 320 */
bcc9ba8b Waiman Long 2018-07-12 321 pcnt = get_cpu_ptr(&nr_dentry_neg);
bcc9ba8b Waiman Long 2018-07-12 322 if ((READ_ONCE(ndblk.nfree) > 0) &&
bcc9ba8b Waiman Long 2018-07-12 323 (*pcnt > neg_dentry_percpu_limit)) {
bcc9ba8b Waiman Long 2018-07-12 324 cnt = __neg_dentry_nfree_dec(*pcnt - neg_dentry_percpu_limit);
bcc9ba8b Waiman Long 2018-07-12 325 *pcnt -= cnt;
bcc9ba8b Waiman Long 2018-07-12 326 }
bcc9ba8b Waiman Long 2018-07-12 327 put_cpu_ptr(&nr_dentry_neg);
bcc9ba8b Waiman Long 2018-07-12 328
2aa8bf46 Waiman Long 2018-07-12 329 if (cnt)
2aa8bf46 Waiman Long 2018-07-12 330 goto out;
2aa8bf46 Waiman Long 2018-07-12 331
bcc9ba8b Waiman Long 2018-07-12 332 /*
2aa8bf46 Waiman Long 2018-07-12 333 * Put out a warning every minute or so if there are just too many
2aa8bf46 Waiman Long 2018-07-12 334 * negative dentries.
bcc9ba8b Waiman Long 2018-07-12 335 */
2aa8bf46 Waiman Long 2018-07-12 336 current_time = jiffies;
bcc9ba8b Waiman Long 2018-07-12 337
2aa8bf46 Waiman Long 2018-07-12 338 if (current_time < ndblk.warn_jiffies + NEG_WARN_PERIOD)
2aa8bf46 Waiman Long 2018-07-12 339 goto out;
2aa8bf46 Waiman Long 2018-07-12 340 /*
2aa8bf46 Waiman Long 2018-07-12 341 * Update the time in ndblk.warn_jiffies and print a warning
2aa8bf46 Waiman Long 2018-07-12 342 * if time update is successful.
2aa8bf46 Waiman Long 2018-07-12 343 */
2aa8bf46 Waiman Long 2018-07-12 344 raw_spin_lock(&ndblk.nfree_lock);
2aa8bf46 Waiman Long 2018-07-12 345 if (current_time < ndblk.warn_jiffies + NEG_WARN_PERIOD) {
2aa8bf46 Waiman Long 2018-07-12 346 raw_spin_unlock(&ndblk.nfree_lock);
2aa8bf46 Waiman Long 2018-07-12 347 goto out;
2aa8bf46 Waiman Long 2018-07-12 348 }
2aa8bf46 Waiman Long 2018-07-12 349 ndblk.warn_jiffies = current_time;
2aa8bf46 Waiman Long 2018-07-12 350 raw_spin_unlock(&ndblk.nfree_lock);
2aa8bf46 Waiman Long 2018-07-12 351
2aa8bf46 Waiman Long 2018-07-12 352 /*
2aa8bf46 Waiman Long 2018-07-12 353 * Get the current negative dentry count & print a warning.
2aa8bf46 Waiman Long 2018-07-12 354 */
2aa8bf46 Waiman Long 2018-07-12 @355 cnt = get_nr_dentry_neg();
2aa8bf46 Waiman Long 2018-07-12 356 pr_warn("Warning: Too many negative dentries (%ld). "
2aa8bf46 Waiman Long 2018-07-12 357 "This warning can be disabled by writing 0 to \"fs/neg-dentry-limit\" or increasing the limit.\n",
2aa8bf46 Waiman Long 2018-07-12 358 cnt);
2aa8bf46 Waiman Long 2018-07-12 359 out:
2aa8bf46 Waiman Long 2018-07-12 360 return;
bcc9ba8b Waiman Long 2018-07-12 361 }
bcc9ba8b Waiman Long 2018-07-12 362
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/fs/dcache.c b/fs/dcache.c index 1fad368..b2c1585 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -139,6 +139,7 @@ struct dentry_stat_t dentry_stat = { * the extra ones will be returned back to the global pool. */ #define NEG_DENTRY_BATCH (1 << 8) +#define NEG_WARN_PERIOD (60 * HZ) /* Print a warning every min */ static struct static_key limit_neg_key = STATIC_KEY_INIT_FALSE; static int neg_dentry_limit_old; @@ -150,6 +151,7 @@ struct dentry_stat_t dentry_stat = { static struct { raw_spinlock_t nfree_lock; long nfree; /* Negative dentry free pool */ + unsigned long warn_jiffies; /* Time when last warning is printed */ } ndblk ____cacheline_aligned_in_smp; proc_handler proc_neg_dentry_limit; @@ -309,6 +311,7 @@ static long __neg_dentry_nfree_dec(long cnt) static noinline void neg_dentry_inc_slowpath(struct dentry *dentry) { long cnt = 0, *pcnt; + unsigned long current_time; /* * Try to move some negative dentry quota from the global free @@ -323,12 +326,38 @@ static noinline void neg_dentry_inc_slowpath(struct dentry *dentry) } put_cpu_ptr(&nr_dentry_neg); + if (cnt) + goto out; + /* - * Put out a warning if there are too many negative dentries. + * Put out a warning every minute or so if there are just too many + * negative dentries. */ - if (!cnt) - pr_warn_once("There are too many negative dentries."); + current_time = jiffies; + + if (current_time < ndblk.warn_jiffies + NEG_WARN_PERIOD) + goto out; + /* + * Update the time in ndblk.warn_jiffies and print a warning + * if time update is successful. + */ + raw_spin_lock(&ndblk.nfree_lock); + if (current_time < ndblk.warn_jiffies + NEG_WARN_PERIOD) { + raw_spin_unlock(&ndblk.nfree_lock); + goto out; + } + ndblk.warn_jiffies = current_time; + raw_spin_unlock(&ndblk.nfree_lock); + /* + * Get the current negative dentry count & print a warning. + */ + cnt = get_nr_dentry_neg(); + pr_warn("Warning: Too many negative dentries (%ld). " + "This warning can be disabled by writing 0 to \"fs/neg-dentry-limit\" or increasing the limit.\n", + cnt); +out: + return; } /*
When there are too many negative dentries, printing a warning once may not get the attention of the system administrator. So it is now change to print a warning every minute until it is turned off by either writing a 0 into fs/neg-dentry-limit or the limit is increased. After that the system administrator can look into the reason why there are so many negative dentries. Note that the warning is printed when the global negative dentry free pool is depleted even if there are space in other percpu negative dentry counts for more. Signed-off-by: Waiman Long <longman@redhat.com> --- fs/dcache.c | 35 ++++++++++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-)