On Mon, 2013-04-15 at 11:15 +0900, Yasuaki Ishimatsu wrote: > When hot removing memory presented at boot time, following messages are shown:
: > The reason why the messages are shown is to release a resource structure, > allocated by bootmem, by kfree(). So when we release a resource structure, > we should check whether it is allocated by bootmem or not. > > But even if we know a resource structure is allocated by bootmem, we cannot > release it since SLxB cannot treat it. So for reusing a resource structure, > this patch remembers it by using bootmem_resource as follows: > > When releasing a resource structure by free_resource(), free_resource() checks > whether the resource structure is allocated by bootmem or not. If it is > allocated by bootmem, free_resource() adds it to bootmem_resource. If it is > not allocated by bootmem, free_resource() release it by kfree(). > > And when getting a new resource structure by get_resource(), get_resource() > checks whether bootmem_resource has released resource structures or not. If > there is a released resource structure, get_resource() returns it. If there is > not a releaed resource structure, get_resource() returns new resource > structure > allocated by kzalloc(). Thanks for fixing this existing issue that also needed to be addressed. I am not able to test this particular case in my test env, so I did not notice it. Can you update this patch to base off of the patch below? Otherwise, it won't apply cleanly. https://lkml.org/lkml/2013/4/11/694 More comments below. > Signed-off-by: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com> > --- > This patch is baseg on following Toshi's works: > Support memory hot-delete to boot memory > https://lkml.org/lkml/2013/4/10/469 > > kernel/resource.c | 72 +++++++++++++++++++++++++++++++++++++++++++--------- > 1 files changed, 59 insertions(+), 13 deletions(-) > > diff --git a/kernel/resource.c b/kernel/resource.c > index 16bfd39..152e9aa 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -21,6 +21,7 @@ > #include <linux/seq_file.h> > #include <linux/device.h> > #include <linux/pfn.h> > +#include <linux/mm.h> > #include <asm/io.h> > > > @@ -50,6 +51,16 @@ struct resource_constraint { > > static DEFINE_RWLOCK(resource_lock); > > +/* > + * For memory hotplug, there is no way to free resource entries allocated > + * by boot mem after the system is up. So for reusing the resource entry > + * we need to remember the resource. > + */ > +struct resource bootmem_resource = { > + .sibling = NULL, > +}; > +static DEFINE_SPINLOCK(bootmem_resource_lock); > + > static void *r_next(struct seq_file *m, void *v, loff_t *pos) > { > struct resource *p = v; > @@ -151,6 +162,42 @@ __initcall(ioresources_init); > > #endif /* CONFIG_PROC_FS */ > > +static void __free_resource(struct resource *res) > +{ > + struct resource *next_res = bootmem_resource.sibling; > + > + bootmem_resource.sibling = res; > + res->sibling = next_res; > +} > + > +static void free_resource(struct resource *res) > +{ You need to add the following if-statement here. Otherwise it hits a page fault when res is NULL. This case happens when a resource entry splits into two entries. if (!res) return; > + if (PageReserved(virt_to_page(res))) { > + spin_lock(&bootmem_resource_lock); > + __free_resource(res); How about simply updating the link here, instead of having it done in __free_resource()? I think it makes it more consistent with get_resource(). res->sibling = bootmem_resource.sibling; bootmem_resource.sibling = res; Thanks, -Toshi > + spin_unlock(&bootmem_resource_lock); > + } else { > + kfree(res); > + } > +} -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
