On Wed, 20 Sep 2000, Roger Larsson wrote:
> Hi,
>
>
> Trying to find out why test9-pre4 freezes with mmap002
> I added a counter for try_again loops.
>
> ... __alloc_pages(...)
>
> int direct_reclaim = 0;
> unsigned int gfp_mask = zonelist->gfp_mask;
> struct page * page = NULL;
> + int try_again_loops = 0;
>
> - - -
>
> + printk("VM: sync kswapd (direct_reclaim: %d) try_again #
> %d\n",
> + direct_reclaim, ++try_again_loops);
> wakeup_kswapd(1);
> goto try_again;
>
>
> Result was surprising:
> direct_reclaim was 1.
> try_again_loops did never stop increasing (note: it is not static,
> and should restart from zero after each success)
>
> Why does this happen?
> a) kswapd did not succeed in freeing a suitable page?
> b) __alloc_pages did not succeed in grabbing the page?
Hi Roger,
A trace of locked up box shows endless repetitions of kswapd aparantly
failing to free anything. What I don't see in the trace snippet below
is reclaim_page(). I wonder if this test in __alloc_pages_limit()
should include an || direct_reclaim.
if (z->free_pages + z->inactive_clean_pages > water_mark) {
struct page *page = NULL;
/* If possible, reclaim a page directly. */
if (direct_reclaim && z->free_pages < z->pages_min + 8)
page = reclaim_page(z);
/* If that fails, fall back to rmqueue. */
if (!page)
page = rmqueue(z, order);
if (page)
return page;
}
dmesg log after breakout:
SysRq: Suspending trace
SysRq: Show Memory
Mem-info:
Free pages: 1404kB ( 0kB HighMem)
( Active: 274, inactive_dirty: 49, inactive_clean: 0, free: 351 (255 510 765) )
0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 1*512kB 0*1024kB 0*2048kB = 512kB)
1*4kB 1*8kB 1*16kB 1*32kB 1*64kB 0*128kB 1*256kB 1*512kB 0*1024kB 0*2048kB = 892kB)
= 0kB)
Swap cache: add 470291, delete 470291, find 212689/658406
Free swap: 199024kB
32752 pages of RAM
0 pages of HIGHMEM
4321 reserved pages
296 pages shared
0 pages swap cached
0 pages in page table cache
Buffer memory: 120kB
SysRq: Terminate All Tasks
trace snippet:
........
c0134aa7 try_to_free_buffers +<13/130> (0.18) pid(3)
c0134a47 sync_page_buffers +<13/60> (0.27) pid(3)
c0117fb3 __wake_up +<13/144> (0.25) pid(3)
c012dea9 __free_pages +<d/28> (0.26) pid(3)
c0134aa7 try_to_free_buffers +<13/130> (0.16) pid(3)
c0134a47 sync_page_buffers +<13/60> (0.33) pid(3)
c0117fb3 __wake_up +<13/144> (0.25) pid(3)
c012dea9 __free_pages +<d/28> (0.20) pid(3)
c012cce7 free_shortage +<13/ac> (0.13) pid(3)
c012df1e nr_free_pages +<e/3c> (0.16) pid(3)
c012df5a nr_inactive_clean_pages +<e/40> (0.16) pid(3)
c012df1e nr_free_pages +<e/3c> (0.21) pid(3)
c014261d shrink_dcache_memory +<d/38> (0.24) pid(3)
c0142280 prune_dcache +<10/120> (0.18) pid(3)
c012a8ea kmem_cache_shrink +<e/58> (0.14) pid(3)
c012a832 is_chained_kmem_cache +<e/60> (0.96) pid(3)
c012a892 __kmem_cache_shrink +<e/58> (0.36) pid(3)
c0143849 shrink_icache_memory +<d/38> (0.24) pid(3)
c014375f prune_icache +<13/f0> (0.14) pid(3)
c01432e4 sync_all_inodes +<10/120> (1.12) pid(3)
c01435ef dispose_list +<f/68> (0.21) pid(3)
c012a8ea kmem_cache_shrink +<e/58> (0.14) pid(3)
c012a832 is_chained_kmem_cache +<e/60> (0.29) pid(3)
c012a892 __kmem_cache_shrink +<e/58> (0.26) pid(3)
c012cde3 refill_inactive +<13/128> (0.12) pid(3)
c012cd8e inactive_shortage +<e/50> (0.14) pid(3)
c012df1e nr_free_pages +<e/3c> (0.18) pid(3)
c012df5a nr_inactive_clean_pages +<e/40> (0.23) pid(3)
c012cce7 free_shortage +<13/ac> (0.13) pid(3)
c012df1e nr_free_pages +<e/3c> (0.21) pid(3)
c012df5a nr_inactive_clean_pages +<e/40> (0.16) pid(3)
c012df1e nr_free_pages +<e/3c> (0.19) pid(3)
c012af3b kmem_cache_reap +<13/1f0> (2.17) pid(3)
c0117bb3 schedule +<13/400> (1.20) pid(3->5)
c0109263 __switch_to +<13/cc> (0.69) pid(5)
c0134c9f flush_dirty_buffers +<13/cc> (0.19) pid(5)
c012df1e nr_free_pages +<e/3c> (0.16) pid(5)
c012df5a nr_inactive_clean_pages +<e/40> (0.20) pid(5)
c0117fb3 __wake_up +<13/144> (0.31) pid(5)
c0117bb3 schedule +<13/400> (1.20) pid(5->141)
c0109263 __switch_to +<13/cc> (0.41) pid(141)
c0118d7d remove_wait_queue +<d/24> (0.40) pid(141)
c012db24 __alloc_pages_limit +<10/b8> (0.35) pid(141)
c012db24 __alloc_pages_limit +<10/b8> (0.23) pid(141)
c012d0d2 wakeup_kswapd +<12/cc> (0.17) pid(141)
c012db24 __alloc_pages_limit +<10/b8> (0.25) pid(141)
c012d0d2 wakeup_kswapd +<12/cc> (0.16) pid(141)
c0118d13 add_wait_queue +<f/38> (0.22) pid(141)
c0117bb3 schedule +<13/400> (1.12) pid(141->144)
c0109263 __switch_to +<13/cc> (0.38) pid(144)
c0118d7d remove_wait_queue +<d/24> (0.33) pid(144)
c012db24 __alloc_pages_limit +<10/b8> (0.22) pid(144)
c012db24 __alloc_pages_limit +<10/b8> (0.20) pid(144)
c012d0d2 wakeup_kswapd +<12/cc> (0.17) pid(144)
c012db24 __alloc_pages_limit +<10/b8> (0.24) pid(144)
c012d0d2 wakeup_kswapd +<12/cc> (0.16) pid(144)
c0118d13 add_wait_queue +<f/38> (0.22) pid(144)
c0117bb3 schedule +<13/400> (1.20) pid(144->1237)
c0109263 __switch_to +<13/cc> (0.36) pid(1237)
c0118d7d remove_wait_queue +<d/24> (0.33) pid(1237)
c012db24 __alloc_pages_limit +<10/b8> (0.22) pid(1237)
c012db24 __alloc_pages_limit +<10/b8> (0.20) pid(1237)
c012d0d2 wakeup_kswapd +<12/cc> (0.17) pid(1237)
c012db24 __alloc_pages_limit +<10/b8> (0.24) pid(1237)
c012d0d2 wakeup_kswapd +<12/cc> (0.19) pid(1237)
c0118d13 add_wait_queue +<f/38> (0.22) pid(1237)
c0117bb3 schedule +<13/400> (1.08) pid(1237->194)
c0109263 __switch_to +<13/cc> (0.37) pid(194)
c0118d7d remove_wait_queue +<d/24> (0.31) pid(194)
c012db24 __alloc_pages_limit +<10/b8> (0.22) pid(194)
c012db24 __alloc_pages_limit +<10/b8> (0.20) pid(194)
c012d0d2 wakeup_kswapd +<12/cc> (0.17) pid(194)
c012db24 __alloc_pages_limit +<10/b8> (0.24) pid(194)
c012d0d2 wakeup_kswapd +<12/cc> (0.16) pid(194)
c0118d13 add_wait_queue +<f/38> (0.22) pid(194)
c0117bb3 schedule +<13/400> (0.99) pid(194->99)
c0109263 __switch_to +<13/cc> (0.38) pid(99)
c0118d7d remove_wait_queue +<d/24> (0.31) pid(99)
c012db24 __alloc_pages_limit +<10/b8> (0.22) pid(99)
c012db24 __alloc_pages_limit +<10/b8> (0.20) pid(99)
c012d0d2 wakeup_kswapd +<12/cc> (0.22) pid(99)
c012db24 __alloc_pages_limit +<10/b8> (0.24) pid(99)
c012d0d2 wakeup_kswapd +<12/cc> (0.16) pid(99)
c0118d13 add_wait_queue +<f/38> (0.22) pid(99)
c0117bb3 schedule +<13/400> (0.89) pid(99->218)
c0109263 __switch_to +<13/cc> (0.38) pid(218)
c0118d7d remove_wait_queue +<d/24> (0.31) pid(218)
c012db24 __alloc_pages_limit +<10/b8> (0.22) pid(218)
c012db24 __alloc_pages_limit +<10/b8> (0.20) pid(218)
c012d0d2 wakeup_kswapd +<12/cc> (0.17) pid(218)
c012db24 __alloc_pages_limit +<10/b8> (0.24) pid(218)
c012d0d2 wakeup_kswapd +<12/cc> (0.18) pid(218)
c0118d13 add_wait_queue +<f/38> (0.22) pid(218)
c0117bb3 schedule +<13/400> (0.90) pid(218->1238)
c0109263 __switch_to +<13/cc> (0.48) pid(1238)
c0118d7d remove_wait_queue +<d/24> (0.31) pid(1238)
c012db24 __alloc_pages_limit +<10/b8> (0.22) pid(1238)
c012db24 __alloc_pages_limit +<10/b8> (0.20) pid(1238)
c012d0d2 wakeup_kswapd +<12/cc> (0.17) pid(1238)
c012db24 __alloc_pages_limit +<10/b8> (0.24) pid(1238)
c012d0d2 wakeup_kswapd +<12/cc> (0.16) pid(1238)
c0118d13 add_wait_queue +<f/38> (0.22) pid(1238)
c0117bb3 schedule +<13/400> (0.53) pid(1238->3)
c0109263 __switch_to +<13/cc> (0.35) pid(3)
c012cbf3 refill_inactive_scan +<13/f4> (0.18) pid(3)
c012b30d age_page_down_nolock +<d/28> (0.16) pid(3)
c012b39b deactivate_page_nolock +<f/254> (0.40) pid(3)
c012cbf3 refill_inactive_scan +<13/f4> (0.16) pid(3)
c012b30d age_page_down_nolock +<d/28> (0.16) pid(3)
c012b39b deactivate_page_nolock +<f/254> (0.32) pid(3)
..........
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