Commit 9661d5bc authored by Yasuaki Ishimatsu's avatar Yasuaki Ishimatsu Committed by Ingo Molnar
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x86/mm/hotplug: Modify PGD entry when removing memory



When hot-adding/removing memory, sync_global_pgds() is called
for synchronizing PGD to PGD entries of all processes MM.  But
when hot-removing memory, sync_global_pgds() does not work
correctly.

At first, sync_global_pgds() checks whether target PGD is none
or not.  And if PGD is none, the PGD is skipped.  But when
hot-removing memory, PGD may be none since PGD may be cleared by
free_pud_table().  So when sync_global_pgds() is called after
hot-removing memory, sync_global_pgds() should not skip PGD even
if the PGD is none.  And sync_global_pgds() must clear PGD
entries of all processes MM.

Currently sync_global_pgds() does not clear PGD entries of all
processes MM when hot-removing memory.  So when hot adding
memory which is same memory range as removed memory after
hot-removing memory, following call traces are shown:

 kernel BUG at arch/x86/mm/init_64.c:206!
 ...
 [<ffffffff815e0c80>] kernel_physical_mapping_init+0x1b2/0x1d2
 [<ffffffff815ced94>] init_memory_mapping+0x1d4/0x380
 [<ffffffff8104aebd>] arch_add_memory+0x3d/0xd0
 [<ffffffff815d03d9>] add_memory+0xb9/0x1b0
 [<ffffffff81352415>] acpi_memory_device_add+0x1af/0x28e
 [<ffffffff81325dc4>] acpi_bus_device_attach+0x8c/0xf0
 [<ffffffff813413b9>] acpi_ns_walk_namespace+0xc8/0x17f
 [<ffffffff81325d38>] ? acpi_bus_type_and_status+0xb7/0xb7
 [<ffffffff81325d38>] ? acpi_bus_type_and_status+0xb7/0xb7
 [<ffffffff813418ed>] acpi_walk_namespace+0x95/0xc5
 [<ffffffff81326b4c>] acpi_bus_scan+0x9a/0xc2
 [<ffffffff81326bff>] acpi_scan_bus_device_check+0x8b/0x12e
 [<ffffffff81326cb5>] acpi_scan_device_check+0x13/0x15
 [<ffffffff81320122>] acpi_os_execute_deferred+0x25/0x32
 [<ffffffff8107e02b>] process_one_work+0x17b/0x460
 [<ffffffff8107edfb>] worker_thread+0x11b/0x400
 [<ffffffff8107ece0>] ? rescuer_thread+0x400/0x400
 [<ffffffff81085aef>] kthread+0xcf/0xe0
 [<ffffffff81085a20>] ? kthread_create_on_node+0x140/0x140
 [<ffffffff815fc76c>] ret_from_fork+0x7c/0xb0
 [<ffffffff81085a20>] ? kthread_create_on_node+0x140/0x140

This patch clears PGD entries of all processes MM when
sync_global_pgds() is called after hot-removing memory
Signed-off-by: default avatarYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: default avatarToshi Kani <toshi.kani@hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5255e0a7
......@@ -115,7 +115,8 @@ static inline void native_pgd_clear(pgd_t *pgd)
native_set_pgd(pgd, native_make_pgd(0));
}
extern void sync_global_pgds(unsigned long start, unsigned long end);
extern void sync_global_pgds(unsigned long start, unsigned long end,
int removed);
/*
* Conversion functions: convert a page and protection to a page entry,
......
......@@ -350,7 +350,7 @@ static void dump_pagetable(unsigned long address)
void vmalloc_sync_all(void)
{
sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END);
sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END, 0);
}
/*
......
......@@ -178,7 +178,7 @@ __setup("noexec32=", nonx32_setup);
* When memory was added/removed make sure all the processes MM have
* suitable PGD entries in the local PGD level page.
*/
void sync_global_pgds(unsigned long start, unsigned long end)
void sync_global_pgds(unsigned long start, unsigned long end, int removed)
{
unsigned long address;
......@@ -186,7 +186,12 @@ void sync_global_pgds(unsigned long start, unsigned long end)
const pgd_t *pgd_ref = pgd_offset_k(address);
struct page *page;
if (pgd_none(*pgd_ref))
/*
* When it is called after memory hot remove, pgd_none()
* returns true. In this case (removed == 1), we must clear
* the PGD entries in the local PGD level page.
*/
if (pgd_none(*pgd_ref) && !removed)
continue;
spin_lock(&pgd_lock);
......@@ -199,12 +204,18 @@ void sync_global_pgds(unsigned long start, unsigned long end)
pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
spin_lock(pgt_lock);
if (pgd_none(*pgd))
set_pgd(pgd, *pgd_ref);
else
if (!pgd_none(*pgd_ref) && !pgd_none(*pgd))
BUG_ON(pgd_page_vaddr(*pgd)
!= pgd_page_vaddr(*pgd_ref));
if (removed) {
if (pgd_none(*pgd_ref) && !pgd_none(*pgd))
pgd_clear(pgd);
} else {
if (pgd_none(*pgd))
set_pgd(pgd, *pgd_ref);
}
spin_unlock(pgt_lock);
}
spin_unlock(&pgd_lock);
......@@ -633,7 +644,7 @@ kernel_physical_mapping_init(unsigned long start,
}
if (pgd_changed)
sync_global_pgds(addr, end - 1);
sync_global_pgds(addr, end - 1, 0);
__flush_tlb_all();
......@@ -995,7 +1006,7 @@ remove_pagetable(unsigned long start, unsigned long end, bool direct)
}
if (pgd_changed)
sync_global_pgds(start, end - 1);
sync_global_pgds(start, end - 1, 1);
flush_tlb_all();
}
......@@ -1342,7 +1353,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
else
err = vmemmap_populate_basepages(start, end, node);
if (!err)
sync_global_pgds(start, end - 1);
sync_global_pgds(start, end - 1, 0);
return err;
}
......
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