Allthough kernel text is always mapped with BATs, we still have
inittext mapped with pages, so TLB miss handling is required
when CONFIG_DEBUG_PAGEALLOC or CONFIG_KFENCE is set.
The final solution should be to set a BAT that also maps inittext
but that BAT then needs to be cleared at end of init, and it will
require more changes to be able to do it properly.
As DEBUG_PAGEALLOC or KFENCE are debugging, performance is not a big
deal so let's fix it simply for now to enable easy stable application.
Reported-by: Maxime Bizon <mbizon(a)freebox.fr>
Fixes: 035b19a15a98 ("powerpc/32s: Always map kernel text and rodata with BATs")
Cc: stable(a)vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy(a)csgroup.eu>
---
arch/powerpc/kernel/head_book3s_32.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 68e5c0a7e99d..2e2a8211b17b 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -421,14 +421,14 @@ InstructionTLBMiss:
*/
/* Get PTE (linux-style) and check access */
mfspr r3,SPRN_IMISS
-#ifdef CONFIG_MODULES
+#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
lis r1, TASK_SIZE@h /* check if kernel address */
cmplw 0,r1,r3
#endif
mfspr r2, SPRN_SDR1
li r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC | _PAGE_USER
rlwinm r2, r2, 28, 0xfffff000
-#ifdef CONFIG_MODULES
+#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
bgt- 112f
lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */
li r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
--
2.33.1
From: Linus Torvalds <torvalds(a)linux-foundation.org>
commit e386dfc56f837da66d00a078e5314bc8382fab83 upstream.
Commit 054aa8d439b9 ("fget: check that the fd still exists after getting
a ref to it") fixed a race with getting a reference to a file just as it
was being closed. It was a fairly minimal patch, and I didn't think
re-checking the file pointer lookup would be a measurable overhead,
since it was all right there and cached.
But I was wrong, as pointed out by the kernel test robot.
The 'poll2' case of the will-it-scale.per_thread_ops benchmark regressed
quite noticeably. Admittedly it seems to be a very artificial test:
doing "poll()" system calls on regular files in a very tight loop in
multiple threads.
That means that basically all the time is spent just looking up file
descriptors without ever doing anything useful with them (not that doing
'poll()' on a regular file is useful to begin with). And as a result it
shows the extra "re-check fd" cost as a sore thumb.
Happily, the regression is fixable by just writing the code to loook up
the fd to be better and clearer. There's still a cost to verify the
file pointer, but now it's basically in the noise even for that
benchmark that does nothing else - and the code is more understandable
and has better comments too.
[ Side note: this patch is also a classic case of one that looks very
messy with the default greedy Myers diff - it's much more legible with
either the patience of histogram diff algorithm ]
Link: https://lore.kernel.org/lkml/20211210053743.GA36420@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/lkml/20211213083154.GA20853@linux.intel.com/
Reported-by: kernel test robot <oliver.sang(a)intel.com>
Tested-by: Carel Si <beibei.si(a)intel.com>
Cc: Jann Horn <jannh(a)google.com>
Cc: Miklos Szeredi <mszeredi(a)redhat.com>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
Signed-off-by: Baokun Li <libaokun1(a)huawei.com>
---
fs/file.c | 72 ++++++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 56 insertions(+), 16 deletions(-)
diff --git a/fs/file.c b/fs/file.c
index 9d02352fa18c..79a76d04c7c3 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -817,28 +817,68 @@ void do_close_on_exec(struct files_struct *files)
spin_unlock(&files->file_lock);
}
-static struct file *__fget_files(struct files_struct *files, unsigned int fd,
- fmode_t mask, unsigned int refs)
+static inline struct file *__fget_files_rcu(struct files_struct *files,
+ unsigned int fd, fmode_t mask, unsigned int refs)
{
- struct file *file;
+ for (;;) {
+ struct file *file;
+ struct fdtable *fdt = rcu_dereference_raw(files->fdt);
+ struct file __rcu **fdentry;
- rcu_read_lock();
-loop:
- file = fcheck_files(files, fd);
- if (file) {
- /* File object ref couldn't be taken.
- * dup2() atomicity guarantee is the reason
- * we loop to catch the new file (or NULL pointer)
+ if (unlikely(fd >= fdt->max_fds))
+ return NULL;
+
+ fdentry = fdt->fd + array_index_nospec(fd, fdt->max_fds);
+ file = rcu_dereference_raw(*fdentry);
+ if (unlikely(!file))
+ return NULL;
+
+ if (unlikely(file->f_mode & mask))
+ return NULL;
+
+ /*
+ * Ok, we have a file pointer. However, because we do
+ * this all locklessly under RCU, we may be racing with
+ * that file being closed.
+ *
+ * Such a race can take two forms:
+ *
+ * (a) the file ref already went down to zero,
+ * and get_file_rcu_many() fails. Just try
+ * again:
*/
- if (file->f_mode & mask)
- file = NULL;
- else if (!get_file_rcu_many(file, refs))
- goto loop;
- else if (__fcheck_files(files, fd) != file) {
+ if (unlikely(!get_file_rcu_many(file, refs)))
+ continue;
+
+ /*
+ * (b) the file table entry has changed under us.
+ * Note that we don't need to re-check the 'fdt->fd'
+ * pointer having changed, because it always goes
+ * hand-in-hand with 'fdt'.
+ *
+ * If so, we need to put our refs and try again.
+ */
+ if (unlikely(rcu_dereference_raw(files->fdt) != fdt) ||
+ unlikely(rcu_dereference_raw(*fdentry) != file)) {
fput_many(file, refs);
- goto loop;
+ continue;
}
+
+ /*
+ * Ok, we have a ref to the file, and checked that it
+ * still exists.
+ */
+ return file;
}
+}
+
+static struct file *__fget_files(struct files_struct *files, unsigned int fd,
+ fmode_t mask, unsigned int refs)
+{
+ struct file *file;
+
+ rcu_read_lock();
+ file = __fget_files_rcu(files, fd, mask, refs);
rcu_read_unlock();
return file;
--
2.31.1
The mmc0 clock gate bit was mistakenly assigned to "i2s" clock.
You can find that the same bit is assigned to "mmc0" too.
It leads to mmc0 hang for a long time after any sound activity
also it prevented PM_SLEEP to work properly.
I guess it was introduced by copy-paste from jz4740 driver
where it is really controls I2S clock gate.
Changelog v2 .. v3:
- Added tags Fixes and Reviewed-by.
Changelog v1 .. v2:
- Added useful info above to the commit itself.
Siarhei Volkau (1):
clk: jz4725b: fix mmc0 clock gating
drivers/clk/ingenic/jz4725b-cgu.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--
2.35.1