| Message ID | 20170124053636.30121-1-lokeshvutla@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi All, On Tuesday 24 January 2017 11:06 AM, Lokesh Vutla wrote: > commit 4a9d4b024a31 ("switch fput to task_work_add") implements a > schedule_work() for completing fput(), but did not guarantee calling > __fput() after unpacking initramfs. Because of this, there is a > possibility that during boot a driver can see ETXTBSY when it tries > to load a binary from initramfs as fput() is still pending on that > binary. This patch makes sure that fput() is completed after unpacking > initramfs. > > Reported-by: Murali Karicheri <m-karicheri2@ti.com> > Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> > --- > Link to RFC: https://patchwork.kernel.org/patch/9520539/ > Changes since v1: > - Moved flush_delayed_fput() before loading default modules. > > Note: Reproduced on TI K2HK EVM. K2HK Queue Manager subsystem driver[1] tries > to load a firmware from initramfs during boot. Sometimes loading of this > firmware fails with error ETXTBSY. Digging a bit more observed that > deny_write_access() is returning ETXTBSY as inode->i_writecount is > 0 > for that file. This is because Unpacking initramfs does a > get_write_access(from open) but hasn't done put_write_access(from fput) > as it hasn't been scheduled yet. > > [1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/soc/ti/knav_qmss_queue.c > > init/initramfs.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/init/initramfs.c b/init/initramfs.c > index b32ad7d97ac9..981f286c1d16 100644 > --- a/init/initramfs.c > +++ b/init/initramfs.c > @@ -18,6 +18,7 @@ > #include <linux/dirent.h> > #include <linux/syscalls.h> > #include <linux/utime.h> > +#include <linux/file.h> > > static ssize_t __init xwrite(int fd, const char *p, size_t count) > { > @@ -647,6 +648,7 @@ static int __init populate_rootfs(void) > printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err); > free_initrd(); > #endif > + flush_delayed_fput(); > /* > * Try loading default modules from initramfs. This gives > * us a chance to load before device_initcalls. > Not sure who else to cc here, get_maintainer.pl gives only LKML. Are there any comments on this patch? Thanks and regards, Lokesh
On Tue, Jan 24, 2017 at 11:06:36AM +0530, Lokesh Vutla wrote: > commit 4a9d4b024a31 ("switch fput to task_work_add") implements a > schedule_work() for completing fput(), but did not guarantee calling > __fput() after unpacking initramfs. Because of this, there is a > possibility that during boot a driver can see ETXTBSY when it tries > to load a binary from initramfs as fput() is still pending on that > binary. This patch makes sure that fput() is completed after unpacking > initramfs. Umm... Do we want it done in kernel_init(), then? I have no objections against calling it in populate_rootfs(), and it looks like a sane place for that, but I wonder if the old callsite would remain needed after that...
On Wednesday 01 February 2017 05:58 PM, Al Viro wrote: > On Tue, Jan 24, 2017 at 11:06:36AM +0530, Lokesh Vutla wrote: >> commit 4a9d4b024a31 ("switch fput to task_work_add") implements a >> schedule_work() for completing fput(), but did not guarantee calling >> __fput() after unpacking initramfs. Because of this, there is a >> possibility that during boot a driver can see ETXTBSY when it tries >> to load a binary from initramfs as fput() is still pending on that >> binary. This patch makes sure that fput() is completed after unpacking >> initramfs. > > Umm... Do we want it done in kernel_init(), then? I have no objections > against calling it in populate_rootfs(), and it looks like a sane place > for that, but I wonder if the old callsite would remain needed after that... > Hmm..You are right, the call in kernel_init() is unnecessary. Will post an updated version. Thanks and regards, Lokesh
diff --git a/init/initramfs.c b/init/initramfs.c index b32ad7d97ac9..981f286c1d16 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -18,6 +18,7 @@ #include <linux/dirent.h> #include <linux/syscalls.h> #include <linux/utime.h> +#include <linux/file.h> static ssize_t __init xwrite(int fd, const char *p, size_t count) { @@ -647,6 +648,7 @@ static int __init populate_rootfs(void) printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err); free_initrd(); #endif + flush_delayed_fput(); /* * Try loading default modules from initramfs. This gives * us a chance to load before device_initcalls.
commit 4a9d4b024a31 ("switch fput to task_work_add") implements a schedule_work() for completing fput(), but did not guarantee calling __fput() after unpacking initramfs. Because of this, there is a possibility that during boot a driver can see ETXTBSY when it tries to load a binary from initramfs as fput() is still pending on that binary. This patch makes sure that fput() is completed after unpacking initramfs. Reported-by: Murali Karicheri <m-karicheri2@ti.com> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> --- Link to RFC: https://patchwork.kernel.org/patch/9520539/ Changes since v1: - Moved flush_delayed_fput() before loading default modules. Note: Reproduced on TI K2HK EVM. K2HK Queue Manager subsystem driver[1] tries to load a firmware from initramfs during boot. Sometimes loading of this firmware fails with error ETXTBSY. Digging a bit more observed that deny_write_access() is returning ETXTBSY as inode->i_writecount is > 0 for that file. This is because Unpacking initramfs does a get_write_access(from open) but hasn't done put_write_access(from fput) as it hasn't been scheduled yet. [1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/soc/ti/knav_qmss_queue.c init/initramfs.c | 2 ++ 1 file changed, 2 insertions(+)